學生單次評核報告
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REPORT 01 · PHYSICS · PAPER 1B · 2024

學生單次評核報告

陳子朗
5A
5A-17
物理科 · 卷一乙

評核日期:2026-08-19 | 報告日期:2026-09-29

本卷得分率 · 60/84 分71.4%
已評核13 大題46 小題
本卷取得71.4%60 / 84 分
失分24 分按本報告分數計算

本卷表現按本卷實得分計算,不代表班級百分位或 DSE 等級。

本卷取得 60/84 分(71.4%)。力和運動表現較穩定;熱和氣體及電和磁是優先鞏固範疇。重點包括熱輻射、質量單位換算、電阻變化及渦流解釋。

已考課題得分率

熱和氣體 6/1250.0%
力和運動 19/2286.4%
波動 16/2176.2%
電和磁 12/2157.1%
放射現象和核能 7/887.5%

範圍:第 1–13 題,共 84 分。待覆核項目已在逐題評核標示。

知識地圖每個節點對應一個實際小題。父層以分數加總;未考內容不列出。

表現穩定 ≥80%待鞏固 60–<80%需改善 <60%

只展示本卷已考內容;百分比反映相關小題的得分,並非對所有概念的全面測量。

熱和氣體6/12 · 50.0%

溫度、熱和內能

熱傳遞方式 · 1(a)100%表現穩定 · 1/1
鋁箔與熱輻射 · 1(b)0%需改善 · 0/2

氣體

力和運動19/22 · 86.4%

力與運動

功與動能 · 3(a)100%表現穩定 · 2/2
自由體圖 · 3(b)100%表現穩定 · 2/2
平拋的鉛直位移 · 3(c)100%表現穩定 · 2/2

圓周運動

向心力計算 · 4(a)(i)100%表現穩定 · 2/2
角速度比較 · 4(b)(i)100%表現穩定 · 1/1

功、能量和動量

波動16/21 · 76.2%

波的本質

縱波的位移圖 · 5(a)0%需改善 · 0/2
最低氣壓區域 · 5(b)(ii)100%表現穩定 · 1/1

光的波動性質

光柵間距 · 6(a)100%表現穩定 · 3/3
波長與條紋間距 · 6(b)100%表現穩定 · 2/2

聲音

氣溫與聲速 · 7(a)100%表現穩定 · 1/1
雷暴距離 · 7(c)(ii)50%需改善 · 1/2

光的折射

折射光線與虛像 · 8(a)100%表現穩定 · 2/2
折射角 · 8(b)100%表現穩定 · 2/2
視深計算 · 8(c)100%表現穩定 · 2/2
電和磁12/21 · 57.1%

靜電學

感應電荷分佈 · 9(a)100%表現穩定 · 2/2

電磁感應

放射現象和核能7/8 · 87.5%

放射衰變

應試技巧依小題主要作答要求分為六類;每小題只歸入一類。這是本卷題型觀察,不是另加的技巧分。

本卷技巧得分率

按實際小題分數計算25%50%75%100%審題與判斷62.5%公式與運算75.9%因果解釋65.2%圖像表達80.0%實驗設計66.7%綜合推論66.7%

外圈 100% · 綜合推論只涉及一小題

審題與判斷 5/862.5%
公式與運算 22/2975.9%
因果解釋 15/2365.2%
圖像表達 12/1580.0%
實驗設計 4/666.7%
綜合推論 2/366.7%

逐題評核

1(a)熱傳遞方式熱和氣體 / 溫度、熱和內能1/1
審題與判斷

題目

一瓶溫度為 4 °C 的水從雪櫃取出,放在桌上。室溫為 30 °C。

指出熱量由周圍環境傳至水瓶的一種方式。

評卷參考

熱傳導或輻射。

學生作答

Radiation from Sun to bottle

學生原稿裁圖
評分點得分結果
指出傳導或輻射1/1已取得

評語與失分分析

已指出輻射,取得此評分點。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

熱傳導或輻射。

1(b)鋁箔與熱輻射熱和氣體 / 溫度、熱和內能0/2
因果解釋

題目

一瓶溫度為 4 °C 的水從雪櫃取出,放在桌上。室溫為 30 °C。

解釋用鋁箔包裹水瓶會否加快水的升溫速率。

評卷參考

不會。鋁箔的銀色表面是輻射的不良吸收體/良好反射體。

學生作答

As Al foil is a good conductor of heat, which speed up the heat transfer from surrounding to bottle

學生原稿裁圖
評分點得分結果
指出不會加快升溫0/1未取得
指出銀色表面不良吸收/良好反射輻射0/1未取得

評語與失分分析

以導熱性解釋鋁箔會加快升溫,忽略銀色表面對輻射的反射作用。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

不會。鋁箔的銀色表面是輻射的不良吸收體/良好反射體。

1(c)(i)凝結水滴的來源熱和氣體 / 溫度、熱和內能0/1
審題與判斷

題目

一瓶溫度為 4 °C 的水從雪櫃取出,放在桌上。室溫為 30 °C。 一段時間後,水瓶表面形成水珠。

指出瓶外水滴的來源。

評卷參考

周圍空氣中的水蒸氣/水分。

學生作答

air

學生原稿裁圖
評分點得分結果
指出空氣中的水蒸氣/水分0/1未取得

評語與失分分析

只寫「air」,未指出水蒸氣,答案欠具體。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

周圍空氣中的水蒸氣/水分。

1(c)(ii)潛熱與質量單位熱和氣體 / 溫度、熱和內能0/2
公式與運算

題目

一瓶溫度為 4 °C 的水從雪櫃取出,放在桌上。室溫為 30 °C。 一段時間後,水瓶表面形成水珠。

瓶外收集到 0.40 g 水滴。估算凝結時釋放的潛熱。水的比汽化潛熱為 2.26 × 10⁶ J kg⁻¹。

評卷參考

E = ml = (0.40 × 10⁻³)(2.26 × 10⁶) = 904 J。

學生作答

E = (0.4)(2.26×10⁶)
= 9.04×10⁵ J

學生原稿裁圖
評分點得分結果
將 0.40 g 換成 kg 並代入潛熱公式0/1未取得
得到 904 J0/1未取得

評語與失分分析

把 0.40 g 當成 0.40 kg,導致答案大了 1000 倍。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

E = ml = (0.40 × 10⁻³)(2.26 × 10⁶) = 904 J。

2(a)(i)原子的平均動能熱和氣體 / 氣體2/2
公式與運算

題目

一個固定體積的密閉容器盛載單原子氣體氬,並維持在溫度 T₀。氬原子的方均根速率為 500 m s⁻¹。每個氬原子的質量為 6.63 × 10⁻²⁶ kg。

氬原子的均方根速率為 500 m s⁻¹,質量為 6.63 × 10⁻²⁶ kg。計算原子的平均動能。

評卷參考

Eₖ = ½mc² = ½(6.63 × 10⁻²⁶)(500)² ≈ 8.29 × 10⁻²¹ J。

學生作答

E_k = 1/2 (6.63×10⁻²⁶)(500)²
= 8.29×10⁻²¹ J

學生原稿裁圖
評分點得分結果
代入平均動能公式1/1已取得
得到約 8.29 × 10⁻²¹ J1/1已取得

評語與失分分析

平均動能公式、代入及答案正確。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

Eₖ = ½mc² = ½(6.63 × 10⁻²⁶)(500)² ≈ 8.29 × 10⁻²¹ J。

2(a)(ii)動能與絕對溫度熱和氣體 / 氣體1/2
公式與運算

題目

一個固定體積的密閉容器盛載單原子氣體氬,並維持在溫度 T₀。氬原子的方均根速率為 500 m s⁻¹。每個氬原子的質量為 6.63 × 10⁻²⁶ kg。

由此或以其他方法求氣體的溫度 T₀(K)。

評卷參考

Eₖ = 3RT₀/(2Nₐ),故 T₀ = 2NₐEₖ/(3R) ≈ 400 K。

學生作答

nRT = 1/3 N m c̄²
3/2 R T / N_A = 1/2 m c̄² = E_k
T = 3.65×10⁻¹⁸ K

學生原稿裁圖
評分點得分結果
運用平均動能與溫度關係1/1已取得
得到約 400 K0/1未取得

評語與失分分析

列出了動能與溫度的正確關係,但最終數值不合理;保留關係式分。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

Eₖ = 3RT₀/(2Nₐ),故 T₀ = 2NₐEₖ/(3R) ≈ 400 K。

2(b)定溫下的均方根速率熱和氣體 / 氣體2/2
因果解釋

題目

一個固定體積的密閉容器盛載單原子氣體氬,並維持在溫度 T₀。氬原子的方均根速率為 500 m s⁻¹。每個氬原子的質量為 6.63 × 10⁻²⁶ kg。

若容器漏出部分氬氣,而溫度維持 T₀,指出並解釋餘下氬原子均方根速率的變化。

評卷參考

溫度不變,原子的平均動能不變,所以均方根速率不變。

學生作答

As temperature unchange,
average kinetic energy of argon unchange.
Thus, c_rms also unchange.

學生原稿裁圖
評分點得分結果
指出溫度不變1/1已取得
推論平均動能及均方根速率不變1/1已取得

評語與失分分析

已連結溫度不變、平均動能不變及均方根速率不變。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

溫度不變,原子的平均動能不變,所以均方根速率不變。

3(a)功與動能力和運動 / 力與運動2/2
公式與運算

題目

質量為 0.20 kg 的小木塊 P 靜止於水平桌面的 A 端。A 至 B 的桌面光滑,B 至 C 的桌面粗糙。圖 3.1 所示的水平力為 0.30 N,A 至 B 的距離為 0.75 m。忽略空氣阻力。

質量 0.20 kg 的滑塊由靜止受水平力 0.30 N 作用,在光滑表面移動 0.75 m 至 B。求其速率。

原題插圖

評卷參考

Fs = ½mv²;0.30 × 0.75 = ½(0.20)v²;v = 1.5 m s⁻¹。

學生作答

WD = F · s
1/2 (0.2) v² = (0.3)(0.75)
v = 1.5 m s⁻¹

學生原稿裁圖
評分點得分結果
代入功—動能關係或等效運動公式1/1已取得
得到 1.5 m s⁻¹1/1已取得

評語與失分分析

正確運用功與動能的關係,得到 1.5 m s⁻¹。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

Fs = ½mv²;0.30 × 0.75 = ½(0.20)v²;v = 1.5 m s⁻¹。

3(b)自由體圖力和運動 / 力與運動2/2
圖像表達待教師校對

題目

質量為 0.20 kg 的小木塊 P 靜止於水平桌面的 A 端。A 至 B 的桌面光滑,B 至 C 的桌面粗糙。圖 3.1 所示的水平力為 0.30 N,A 至 B 的距離為 0.75 m。忽略空氣阻力。

滑塊到達 B 時撤去水平外力。它繼續在粗糙表面由 B 移至 C,在自由體圖畫出及標示所有作用力。

原題插圖
原題插圖

評卷參考

三個力:向上支持力、向下重力、向左摩擦力。

評卷參考原圖 · 第 59 頁

學生作答

本小題以圖像作答,請對照下方原稿。

學生原稿裁圖
評分點得分結果
支持力及重力的方向與標示1/1已取得
摩擦力的方向與標示1/1已取得

評語與失分分析

原稿畫出支持力、重力及摩擦力;方向和名稱均取得分數。

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

三個力:向上支持力、向下重力、向左摩擦力。

3(c)平拋的鉛直位移力和運動 / 力與運動2/2
公式與運算

題目

質量為 0.20 kg 的小木塊 P 靜止於水平桌面的 A 端。A 至 B 的桌面光滑,B 至 C 的桌面粗糙。圖 3.1 所示的水平力為 0.30 N,A 至 B 的距離為 0.75 m。忽略空氣阻力。

滑塊由桌邊 C 飛出後,經 0.35 s 抵達地面 K。估算桌子的高度。

原題插圖

評卷參考

h = ½gt² = ½(9.81)(0.35)² ≈ 0.601 m。

學生作答

s_y = u_y t + 1/2 a_y t²
= 0 + 1/2 (9.81)(0.35)²
∴ height = 0.601 m

學生原稿裁圖
評分點得分結果
代入 h = ½gt²1/1已取得
得到約 0.601 m1/1已取得

評語與失分分析

以鉛直初速為零處理下墜,列式及高度正確。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

h = ½gt² = ½(9.81)(0.35)² ≈ 0.601 m。

4(a)(i)向心力計算力和運動 / 圓周運動2/2
公式與運算

題目

半徑為 0.50 m 的球體繞鉛直軸 ACB 以恆定角速率 6 rad s⁻¹ 旋轉,C 為球心。質量為 0.020 kg 的小塊塑膠泥 P 黏在球面上,在通過 C 的水平平面內旋轉。

質量 0.020 kg 的膠泥 P 以角速度 6 rad s⁻¹、半徑 0.50 m 作圓周運動。求向心力。

原題插圖

評卷參考

F = mω²r = (0.020)(6²)(0.50) = 0.36 N。

學生作答

F_c = m ω² r
= (0.02)(6)²(0.5)
= 0.36 N

學生原稿裁圖
評分點得分結果
代入 F = mω²r1/1已取得
得到 0.36 N1/1已取得

評語與失分分析

向心力公式、質量單位及數值均正確。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

F = mω²r = (0.020)(6²)(0.50) = 0.36 N。

4(a)(ii)離開圓周時的切線方向力和運動 / 圓周運動1/1
圖像表達待教師校對

題目

半徑為 0.50 m 的球體繞鉛直軸 ACB 以恆定角速率 6 rad s⁻¹ 旋轉,C 為球心。質量為 0.020 kg 的小塊塑膠泥 P 黏在球面上,在通過 C 的水平平面內旋轉。

球體加速旋轉,P 最終在圖示位置離開球面。在俯視圖上指出 P 剛離開時的運動方向。

原題插圖

評卷參考

由 P 點沿圓周切線、按原來旋轉方向畫箭頭;圖示為左下方。速度不指向圓心。

評卷參考原圖 · 第 59 頁

學生作答

本小題以圖像作答,請對照下方原稿。

學生原稿裁圖
評分點得分結果
沿 P 點切線畫出離開方向1/1已取得

評語與失分分析

離開圓周一刻的速度沿切線;原稿箭頭符合此方向。

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

由 P 點沿圓周切線、按原來旋轉方向畫箭頭;圖示為左下方。速度不指向圓心。

4(b)(i)角速度比較力和運動 / 圓周運動1/1
審題與判斷

題目

半徑為 0.50 m 的球體繞鉛直軸 ACB 以恆定角速率 6 rad s⁻¹ 旋轉,C 為球心。質量為 0.020 kg 的小塊塑膠泥 P 黏在球面上,在通過 C 的水平平面內旋轉。 另一小塊塑膠泥 Q 黏在球面上,如圖 4.2 所示。

指出同一旋轉球體上的 P 和 Q 是否具有相同角速度。

原題插圖

評卷參考

角速度相同。

學生作答

Yes

學生原稿裁圖
評分點得分結果
指出相同角速度1/1已取得

評語與失分分析

同一剛體上的兩點角速度相同,判斷正確。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

角速度相同。

4(b)(ii)向心加速度與半徑力和運動 / 圓周運動2/2
因果解釋

題目

半徑為 0.50 m 的球體繞鉛直軸 ACB 以恆定角速率 6 rad s⁻¹ 旋轉,C 為球心。質量為 0.020 kg 的小塊塑膠泥 P 黏在球面上,在通過 C 的水平平面內旋轉。 另一小塊塑膠泥 Q 黏在球面上,如圖 4.2 所示。

解釋 P 和 Q 的向心加速度大小是否相同。

原題插圖

評卷參考

a = ω²r;兩者 ω 相同,而 Q 的旋轉半徑較小,所以 aQ < aP。

學生作答

NO. As r_Q < r_P
a_Q < a_P

學生原稿裁圖
評分點得分結果
指出 Q 的向心加速度較小1/1已取得
以 Q 的半徑較小解釋1/1已取得

評語與失分分析

正確指出半徑較小的 Q 向心加速度較小。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

a = ω²r;兩者 ω 相同,而 Q 的旋轉半徑較小,所以 aQ < aP。

5(a)縱波的位移圖波動 / 波的本質0/2
圖像表達待教師校對

題目

圖 5.1 顯示揚聲器產生的聲波在某一瞬間的空氣粒子分布。聲波向右傳播,P、Q、R、S、T 為圖中標示的區域。

根據空氣粒子的瞬時分佈,在網格上畫出位移—距離圖。向右的位移取正值。

原題插圖
原題插圖

評卷參考

P、R、T 為零位移;Q、S 的位移為相反極值。由 P 起先向下至 Q 的波谷,再經 R 回到零位移,至 S 的波峰。

評卷參考原圖 · 第 60 頁

學生作答

本小題以圖像作答,請對照下方原稿。

學生原稿裁圖
評分點得分結果
曲線起點及首段方向正確0/1未取得
波長、零位移及極值位置正確0/1未取得

評語與失分分析

位移曲線起點及相位與粒子分佈不符。不能把粒子密度直接當作位移。

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

P、R、T 為零位移;Q、S 的位移為相反極值。由 P 起先向下至 Q 的波谷,再經 R 回到零位移,至 S 的波峰。

5(b)(i)粒子的最高速率波動 / 波的本質0/1
審題與判斷待教師校對

題目

圖 5.1 顯示揚聲器產生的聲波在某一瞬間的空氣粒子分布。聲波向右傳播,P、Q、R、S、T 為圖中標示的區域。

在 P、Q、R、S、T 中指出一個粒子運動速率最大的區域。

原題插圖

評卷參考

P、R、T 中任一個區域。

學生作答

P , R , T

學生原稿裁圖
評分點得分結果
指出 P、R、T 中其中一個區域0/1未取得

評語與失分分析

原答列出 P、R、T,均在參考答案之列。原判因多選而給 0/1;此項保留給教師校對。

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

P、R、T 中任一個區域。

5(b)(ii)最低氣壓區域波動 / 波的本質1/1
審題與判斷

題目

圖 5.1 顯示揚聲器產生的聲波在某一瞬間的空氣粒子分布。聲波向右傳播,P、Q、R、S、T 為圖中標示的區域。

指出圖示瞬間氣壓最低的區域。

原題插圖

評卷參考

R;疏落中心的氣壓最低。

學生作答

R

學生原稿裁圖
評分點得分結果
指出 R1/1已取得

評語與失分分析

選出 R,符合最低氣壓的疏落中心。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

R;疏落中心的氣壓最低。

6(a)光柵間距波動 / 光的波動性質3/3
公式與運算

題目

除去光碟(CD)的保護層及反射層後,光碟成為具有等距平行狹縫的衍射光柵[圖 6.1(a)]。圖 6.1(b) 的雷射裝置用來量度狹縫間距 d。光柵與屏幕相距 L = 0.10 m;兩個一級亮紋相距 x = 0.092 m;紅色雷射光的波長 λ = 650 nm。

利用原圖所示的激光波長、屏幕距離及亮點間距,估算光柵間距 d。

原題插圖

評卷參考

tan θ = (0.092/2)/0.10;d sin θ = λ;d ≈ 1.56 × 10⁻⁶ m。

學生作答

d sin θ = n λ
d sin ( tan⁻¹ ( 0.092/2 / 0.1 ) ) = (1)(650 × 10⁻⁹)
d = 1.56 × 10⁻⁶ m

學生原稿裁圖
評分點得分結果
正確計算衍射角1/1已取得
代入光柵方程1/1已取得
得到約 1.56 μm1/1已取得

評語與失分分析

以正切關係求角度,再代入光柵方程,計算完整。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

tan θ = (0.092/2)/0.10;d sin θ = λ;d ≈ 1.56 × 10⁻⁶ m。

6(b)波長與條紋間距波動 / 光的波動性質2/2
因果解釋

題目

除去光碟(CD)的保護層及反射層後,光碟成為具有等距平行狹縫的衍射光柵[圖 6.1(a)]。圖 6.1(b) 的雷射裝置用來量度狹縫間距 d。光柵與屏幕相距 L = 0.10 m;兩個一級亮紋相距 x = 0.092 m;紅色雷射光的波長 λ = 650 nm。

若改用綠色激光,指出並解釋亮點間距 x 的變化。

原題插圖

評卷參考

x 減少。綠光波長較短,故衍射角較小,亮點間距亦較小。

學生作答

Decrease .
As green laser has shorter wavelength, sin θ reduce
θ reduce . Thus x reduce .

學生原稿裁圖
評分點得分結果
指出 x 減少1/1已取得
以波長及衍射角減少解釋1/1已取得

評語與失分分析

清楚連結波長減少、衍射角減少及間距減少。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

x 減少。綠光波長較短,故衍射角較小,亮點間距亦較小。

7(a)氣溫與聲速波動 / 聲音1/1
審題與判斷

題目

圖 7.1 顯示聲速隨空氣溫度的變化。

參照圖線,指出聲速與空氣溫度的關係。

原題插圖

評卷參考

空氣溫度愈高,聲速愈大;圖示近似線性增加。

學生作答

Speed of sound increase when air temperature increase.

學生原稿裁圖
評分點得分結果
指出氣溫上升時聲速增加1/1已取得

評語與失分分析

正確讀出溫度上升時聲速增加。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

空氣溫度愈高,聲速愈大;圖示近似線性增加。

7(b)聲波在空氣層的折射波動 / 聲音2/2
因果解釋

題目

夜間地面冷卻。圖 7.2 顯示聲音從遠處鐘樓傳至觀察者的路徑。

利用不同高度空氣層的溫度差,解釋圖 7.2 中聲波向地面彎曲的情況。

原題插圖

評卷參考

近地面空氣較冷、聲速較低;聲波由上方較暖空氣傳入下方較冷空氣時向法線偏折,故路徑向地面彎曲。

學生作答

Temperature decrease from sky to ground uniformly.
As sound travel from fast region to slow region, it bends toward to normal of air layers.
Thus, sound moves toward ground.

學生原稿裁圖
學生原稿裁圖
評分點得分結果
指出近地面較冷/上方較暖1/1已取得
以聲速差異及折射方向解釋1/1已取得

評語與失分分析

已交代上暖下冷、聲速差異及聲波向下折射。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

近地面空氣較冷、聲速較低;聲波由上方較暖空氣傳入下方較冷空氣時向法線偏折,故路徑向地面彎曲。

7(c)(i)光速與聲速的比值波動 / 聲音0/1
公式與運算

題目

圖 7.1 顯示聲速隨空氣溫度的變化。 已知空氣溫度為 10 °C。參考圖 7.1。

估算光速與聲速的比值。

原題插圖

評卷參考

(3.00 × 10⁸)/337 ≈ 8.90 × 10⁵。

學生作答

[刪去: c / v]

c / v = (3 × 10⁸) / 337
= 8.90 × 10⁶

學生原稿裁圖
評分點得分結果
得到約 8.90 × 10⁵0/1未取得

評語與失分分析

算式正確,但答案的十進位次方錯了一位。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

(3.00 × 10⁸)/337 ≈ 8.90 × 10⁵。

7(c)(ii)雷暴距離波動 / 聲音1/2
公式與運算待教師校對

題目

圖 7.1 顯示聲速隨空氣溫度的變化。 已知空氣溫度為 10 °C。參考圖 7.1。

觀察者在看見閃電 3.0 s 後聽到雷聲,估算雷暴距離。

原題插圖

評卷參考

d ≈ 337 × 3.0 = 1011 m;約 1.01 km。

學生作答

⇒ [刪去: d = c · t]
[刪去: d = v · (t + 3)]

[刪去: 1 = c/v · t / (t + 3)]

[刪去: v/c t + v/c · 3 = t]

t = 3.37 × 10⁻⁶ s

∴ d = c · t = 1010 m

學生原稿裁圖
評分點得分結果
列出距離計算的代入步驟0/1未取得
得到約 1010–1011 m1/1已取得

評語與失分分析

以光的傳播時間求得 1010 m;原判只給結果分。替代解法的步驟分須連同刪改痕跡校對。

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

d ≈ 337 × 3.0 = 1011 m;約 1.01 km。

8(a)折射光線與虛像波動 / 光的折射2/2
圖像表達待教師校對

題目

圖 8.1 顯示一支放在水杯中的鉛筆,觀察者鉛直向下觀看。水的折射率為 1.33。光線 P 和 Q 由鉛筆尖 O 發出,Q 沿鉛直方向。圖並非按比例繪畫。

在圖 8.1 完成光線路徑,並以 I 標示觀察者所見的 O 的像。

原題插圖

評卷參考

光線由水進入空氣時偏離法線。將折射光線反向延長,交於 O 上方的虛像 I。

評卷參考原圖 · 第 61 頁

學生作答

本小題以圖像作答,請對照下方原稿。

學生原稿裁圖
評分點得分結果
完成折射光線及方向1/1已取得
反向延長光線並標示虛像 I1/1已取得

評語與失分分析

原圖已畫出折射光線及虛像;原系統標記圖像清晰度需覆核。

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

光線由水進入空氣時偏離法線。將折射光線反向延長,交於 O 上方的虛像 I。

8(b)折射角波動 / 光的折射2/2
公式與運算

題目

圖 8.1 顯示一支放在水杯中的鉛筆,觀察者鉛直向下觀看。水的折射率為 1.33。光線 P 和 Q 由鉛筆尖 O 發出,Q 沿鉛直方向。圖並非按比例繪畫。

光線 P 和 Q 的夾角為 1.5°,求 P 的折射角。

原題插圖

評卷參考

sin r = 1.33 sin 1.5°;r ≈ 2.00°。

學生作答

1 sin θ = 1.33 sin 1.5°
θ = 2.00°

學生原稿裁圖
評分點得分結果
代入斯涅爾定律1/1已取得
得到約 2.00°1/1已取得

評語與失分分析

斯涅爾定律的代入及折射角正確。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

sin r = 1.33 sin 1.5°;r ≈ 2.00°。

8(c)視深計算波動 / 光的折射2/2
公式與運算

題目

圖 8.1 顯示一支放在水杯中的鉛筆,觀察者鉛直向下觀看。水的折射率為 1.33。光線 P 和 Q 由鉛筆尖 O 發出,Q 沿鉛直方向。圖並非按比例繪畫。

水深為 0.10 m,求像 I 與水面的距離。

原題插圖

評卷參考

h′ = 0.10 tan 1.5° / tan 2.00° ≈ 0.0752 m。

學生作答

⇒ PQ = 0.1 tan 1.5°
[刪去: tan(2.00°) = PQ / d_req.]

d_req. = (0.1 tan 1.5°) / tan(2.00°)
d = 0.0752 m

學生原稿裁圖
評分點得分結果
建立視深與三角比關係1/1已取得
得到約 0.075 m1/1已取得

評語與失分分析

以三角比求出正確的視深。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

h′ = 0.10 tan 1.5° / tan 2.00° ≈ 0.0752 m。

9(a)感應電荷分佈電和磁 / 靜電學2/2
圖像表達待教師校對

題目

圖 9.1 中,兩個相同的導電輕球 P 和 Q 彼此靠近但不接觸,並放在絕緣支架上。兩球最初均不帶電。一支帶負電的塑膠棒靠近 Q,但不接觸球體。

在圖 9.1 畫出 P 和 Q 上的電荷分佈。

原題插圖

評卷參考

兩球均出現電荷分離:P 和 Q 各自的左側帶負電,右側帶正電,如評卷參考原圖所示。兩球互不接觸,亦沒有接觸塑膠棒。

評卷參考原圖 · 第 62 頁

學生作答

本小題以圖像作答,請對照下方原稿。

學生原稿裁圖
評分點得分結果
Q 球的電荷分佈1/1已取得
P 球的電荷分佈1/1已取得

評語與失分分析

原系統給予圖像滿分,但電荷符號的清晰度需教師對照裁圖確認。

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

兩球均出現電荷分離:P 和 Q 各自的左側帶負電,右側帶正電,如評卷參考原圖所示。兩球互不接觸,亦沒有接觸塑膠棒。

9(b)帶電棒的電荷守恆電和磁 / 靜電學1/2
因果解釋

題目

圖 9.1 中,兩個相同的導電輕球 P 和 Q 彼此靠近但不接觸,並放在絕緣支架上。兩球最初均不帶電。一支帶負電的塑膠棒靠近 Q,但不接觸球體。 塑膠棒保持在圖示位置時,學生用手指短暫觸碰 P,然後移走塑膠棒。

解釋塑膠棒上的電荷量會否減少。

原題插圖

評卷參考

不會。帶電棒沒有接觸導體,沒有電荷轉移;導體內發生靜電感應。

學生作答

No. As plastic rod doesn't earthed.

學生原稿裁圖
評分點得分結果
指出棒上電荷量不變1/1已取得
以無接觸/無電荷轉移的感應解釋0/1未取得

評語與失分分析

判斷電荷量不變正確,但「沒有接地」不足以解釋沒有電荷轉移。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

不會。帶電棒沒有接觸導體,沒有電荷轉移;導體內發生靜電感應。

9(c)辨別未知電荷極性電和磁 / 靜電學1/2
實驗設計

題目

圖 9.1 中,兩個相同的導電輕球 P 和 Q 彼此靠近但不接觸,並放在絕緣支架上。兩球最初均不帶電。一支帶負電的塑膠棒靠近 Q,但不接觸球體。 塑膠棒保持在圖示位置時,學生用手指短暫觸碰 P,然後移走塑膠棒。

兩球以尼龍線分別懸掛並相距甚遠,解釋如何用其中一球判斷另一帶電棒的未知極性。

原題插圖

評卷參考

將未知帶電棒靠近已知帶正電的 P 球而不接觸;排斥表示棒帶正電,吸引表示棒帶負電。

學生作答

By previous action, P is positively charged and Q is neutral.
Thus, use P.
If the rod is positive, P repulse. If rod is negative P attracted.

學生原稿裁圖
評分點得分結果
描述靠近但不接觸的操作0/1未取得
按排斥/吸引判別極性1/1已取得

評語與失分分析

吸引/排斥的判斷正確,欠「靠近但不接觸」的操作描述。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

將未知帶電棒靠近已知帶正電的 P 球而不接觸;排斥表示棒帶正電,吸引表示棒帶負電。

10(a)能量守恆實驗力和運動 / 功、能量和動量3/4
實驗設計待教師校對

題目

圖 10.1 中,一條不可伸長的細繩下端連接小金屬球,上端 O 固定在支架上。量角器固定於支架,位於細繩後方。

寫出使用圖示裝置驗證能量守恆的實驗步驟。

原題插圖

評卷參考

記錄初始非零角度;保持繩拉緊並由靜止釋放;量度另一側最高角度;比較兩側角度/高度,以檢驗機械能守恆。

學生作答

Place the small metal ball at 0° of protractor with the string straight.
Release the ball and record the maximum degree that ball can reach at another side of protractor.
Repeat the experiment at different degree.

Note that ball must reach the other side with same degree (i.e. degree ) as released.

Thus, Potential energy of ball is conserved.

學生原稿裁圖
評分點得分結果
記錄明確初始非零角度0/1未取得
繩拉緊並由靜止釋放1/1已取得
量度另一側最高角度1/1已取得
比較角度/高度以檢驗能量守恆1/1已取得

評語與失分分析

已寫釋放、量度另一側角度及比較,初始非零角度的設定不夠明確。

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

記錄初始非零角度;保持繩拉緊並由靜止釋放;量度另一側最高角度;比較兩側角度/高度,以檢驗機械能守恆。

10(b)(i)(I)碰撞方向的動量守恆力和運動 / 功、能量和動量1/1
因果解釋

題目

圖 10.2 的牛頓擺由五個相同金屬球組成,各球由等長、不可伸長的輕繩懸掛在固定水平支架上。A 和 B 一起稍微向左移並從靜止釋放。碰撞後,A 和 B 停下,而 D 和 E 一起稍微向右擺動。忽略空氣阻力。

雖然繩張力是外力,解釋為何此碰撞仍可應用動量守恆定律。

原題插圖

評卷參考

張力與碰撞方向垂直,在水平方向沒有淨外力/外衝量,故水平方向動量守恆。

學生作答

As the direction of tension and the direction of collision is perpendicular to each other.

學生原稿裁圖
評分點得分結果
指出張力與碰撞方向垂直1/1已取得

評語與失分分析

正確指出張力與碰撞方向互相垂直。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

張力與碰撞方向垂直,在水平方向沒有淨外力/外衝量,故水平方向動量守恆。

10(b)(i)(II)牛頓搖籃的能量檢驗力和運動 / 功、能量和動量2/3
綜合推論

題目

圖 10.2 的牛頓擺由五個相同金屬球組成,各球由等長、不可伸長的輕繩懸掛在固定水平支架上。A 和 B 一起稍微向左移並從靜止釋放。碰撞後,A 和 B 停下,而 D 和 E 一起稍微向右擺動。忽略空氣阻力。

兩球 A、B 各以 0.50 m s⁻¹ 碰撞,每球質量 0.020 kg。假設只有 E 球離開,求其速率,並據此解釋為何這情況不可能發生。

原題插圖

評卷參考

2m(0.50) = mvE,vE = 1.0 m s⁻¹。初動能 0.005 J,假設的末動能 0.010 J,末動能較大,故不可能只有 E 以該速率離開。

學生作答

p_AB = p_E
(0.02 × 2)(0.5) = (0.02) v_E
v_E = 1 m s⁻¹

KE_AB = ½ (0.02 × 2)(0.5)² = 5 × 10⁻³ J
KE_E = ½ (0.02)(1)² = 0.01 J ≠ KE_AB
if only one ball out, energy of system does not conserved.

學生原稿裁圖
評分點得分結果
用動量守恆求 vE1/1已取得
計算初、末動能1/1已取得
指出末動能較大,故假設不可能0/1未取得

評語與失分分析

動量和動能計算正確;還需明確指出末動能大於初動能,所以假設不可能。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

2m(0.50) = mvE,vE = 1.0 m s⁻¹。初動能 0.005 J,假設的末動能 0.010 J,末動能較大,故不可能只有 E 以該速率離開。

10(b)(ii)碰撞的彈性力和運動 / 功、能量和動量1/2
因果解釋

題目

圖 10.2 的牛頓擺由五個相同金屬球組成,各球由等長、不可伸長的輕繩懸掛在固定水平支架上。A 和 B 一起稍微向左移並從靜止釋放。碰撞後,A 和 B 停下,而 D 和 E 一起稍微向右擺動。忽略空氣阻力。

碰撞持續一段時間後整套裝置停止,討論碰撞是否完全彈性。

原題插圖

評卷參考

不完全彈性。部分動能轉化為內能及聲能,所以總動能不守恆。

學生作答

No. As external force act on the system (i.e. air resistance) then eventually returns to rest.

學生原稿裁圖
評分點得分結果
指出不完全彈性1/1已取得
指出碰撞時動能轉化為聲能/內能0/1未取得

評語與失分分析

「不完全彈性」判斷正確;以空氣阻力解釋未直接回應碰撞中的動能轉化。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

不完全彈性。部分動能轉化為內能及聲能,所以總動能不守恆。

11(a)金屬箔的電阻變化電和磁 / 電阻與電路0/2
因果解釋待教師校對

題目

閱讀以下有關形變感應器的資料。圖 11.1(a) 的簡單感應裝置由固定在塑膠底板上的薄、平、長方形金屬箔組成。長度為 l、闊度為 w 的金屬箔受拉伸後,如圖 11.1(b) 般變形,電阻因而改變。把装置接至合適電路,即可藉電路參數(例如電壓)的變化監測形變。

金屬箔被拉長,厚度及電阻率不變。指出並解釋 XY 之間的電阻如何改變。

原題插圖

評卷參考

R = ρl/A;l 增加,闊度減少令 A 減少,所以 R 增加。

學生作答

[刪去: R = ρ l / A]

R ∝ l
When foil is stretched, length XY increase.
∴ Resistance increase.

學生原稿裁圖
評分點得分結果
同時指出長度增加及截面積減少0/1未取得
根據 R = ρl/A 解釋電阻增加0/1未取得

評語與失分分析

已指出長度及電阻增加,但未討論橫截面積減少。原判 0/2 的部分給分待校對。

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

R = ρl/A;l 增加,闊度減少令 A 減少,所以 R 增加。

11(b)(i)串聯支路的電壓電和磁 / 電阻與電路1/1
公式與運算

題目

圖 11.2 的電路有四個電阻 R₁、R₂、R₃、R₄,接至輸入電壓 Vᵢₙ。Vₒᵤₜ 是 DB 兩點間的電壓。

電流 I₁ 流經支路 ABC,寫出 Vᵢₙ、I₁、R₁、R₂ 的關係式。

原題插圖

評卷參考

Vᵢₙ = I₁(R₁ + R₂)。

學生作答

V_in = I₁ (R₁ + R₂)

學生原稿裁圖
評分點得分結果
寫出 Vᵢₙ = I₁(R₁+R₂)1/1已取得

評語與失分分析

已正確建立串聯支路的電壓關係。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

Vᵢₙ = I₁(R₁ + R₂)。

11(b)(ii)電橋輸出的百分比變化電和磁 / 電阻與電路1/2
公式與運算

題目

圖 11.2 的電路有四個電阻 R₁、R₂、R₃、R₄,接至輸入電壓 Vᵢₙ。Vₒᵤₜ 是 DB 兩點間的電壓。

R₄ 由 500 Ω 增至 501 Ω;其餘三個電阻均為 470 Ω。求 Vₒᵤₜ/Vᵢₙ 的百分比變化。

原題插圖

評卷參考

原比值 = 500/970 − 1/2 ≈ 0.0154639;新比值 = 501/971 − 1/2 ≈ 0.0159629;增加約 3.23%。

學生作答

( V_out / V_in )' = 501 / (470 + 501) - 470 / (470 + 470)

V_out / V_in = 500 / (470 + 500) - 470 / (470 + 470)

% Δ V_out / V_in = [ ( V_out / V_in )' - V_out / V_in ] / ( V_out / V_in ) × 100%
= 0.0972%

學生原稿裁圖
評分點得分結果
代入前後兩個電壓比值1/1已取得
得到增加約 3.23%0/1未取得

評語與失分分析

新舊電壓比值的列式正確,但百分比運算結果有誤。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

原比值 = 500/970 − 1/2 ≈ 0.0154639;新比值 = 501/971 − 1/2 ≈ 0.0159629;增加約 3.23%。

11(b)(iii)(I)裂紋增長的判讀電和磁 / 電阻與電路1/1
審題與判斷

題目

感應器 S₁、S₂、S₃、S₄ 接至合適電路並固定在天花 ABCD,如圖 11.3 所示,以監測裂縫 ①、②、③ 的增長。數星期後,偵測到的形變程度依次為 S₁ > S₂ > S₃ > S₄。

推斷裂紋 ①、②、③ 中哪一道增長最多。

原題插圖

評卷參考

裂紋 ①。

學生作答

①

學生原稿裁圖
評分點得分結果
指出裂紋 ①1/1已取得

評語與失分分析

正確選出裂紋 ①。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

裂紋 ①。

11(b)(iii)(II)伸展方向電和磁 / 電阻與電路0/1
審題與判斷

題目

感應器 S₁、S₂、S₃、S₄ 接至合適電路並固定在天花 ABCD,如圖 11.3 所示,以監測裂縫 ①、②、③ 的增長。數星期後,偵測到的形變程度依次為 S₁ > S₂ > S₃ > S₄。

推斷天花板最可能沿 AB、BC 或 AC 哪個方向伸展。

原題插圖

評卷參考

沿 AB 方向。

學生作答

AC

學生原稿裁圖
評分點得分結果
指出方向 AB0/1未取得

評語與失分分析

原答 AC 與參考方向 AB 不符。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

沿 AB 方向。

12(a)圓形線圈的磁場電和磁 / 電磁感應2/2
圖像表達待教師校對

題目

圖 12.1 顯示一個數匝線圈,電流 I 的方向如圖所示。

按圖示電流方向,畫出圓形線圈所產生的磁場圖樣。

原題插圖

評卷參考

畫出穿過線圈的磁場圖樣,箭頭方向如參考圖般向下。評卷參考亦接受因對電流方向有不同理解而畫出的向上箭頭;評分分別考慮方向及磁場圖樣。

評卷參考原圖 · 第 65 頁

學生作答

本小題以圖像作答,請對照下方原稿。

學生原稿裁圖
評分點得分結果
磁力線圖樣正確1/1已取得
線圈中心磁場方向正確1/1已取得

評語與失分分析

磁力線圖樣及中心方向取得兩分。

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

畫出穿過線圈的磁場圖樣,箭頭方向如參考圖般向下。評卷參考亦接受因對電流方向有不同理解而畫出的向上箭頭;評分分別考慮方向及磁場圖樣。

12(b)(i)接收線圈的感應電壓電和磁 / 電磁感應2/2
因果解釋

題目

圖 12.2(a) 中,線圈接至交流電源作為發射線圈 T。連接陰極射線示波器(CRO)的接收線圈 R 放在 T 正上方。圖 12.2(b) 顯示 R 的電壓隨時間的變化。

解釋接收線圈 R 的電壓如何產生。

原題插圖

評卷參考

發射線圈的交流電產生改變的磁場/磁通,接收線圈因電磁感應產生電動勢。

學生作答

As coil T is connected to an a.c., current is induced in coil R due to changing of B-field from T.
Thus, voltage is induced in R.

學生原稿裁圖
評分點得分結果
指出交流電產生改變的磁場1/1已取得
指出磁通改變產生感應電動勢1/1已取得

評語與失分分析

已指出交流電令磁場改變,從而在接收線圈產生感應電壓。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

發射線圈的交流電產生改變的磁場/磁通,接收線圈因電磁感應產生電動勢。

12(b)(ii)頻率加倍後的波形電和磁 / 電磁感應1/2
圖像表達待教師校對

題目

圖 12.2(a) 中,線圈接至交流電源作為發射線圈 T。連接陰極射線示波器(CRO)的接收線圈 R 放在 T 正上方。圖 12.2(b) 顯示 R 的電壓隨時間的變化。

交流電源的頻率加倍,在圖上畫出新的示波器波形。

原題插圖

評卷參考

週期減半、頻率加倍;發射電流振幅不變時,磁通改變率加倍,感應電壓振幅亦加倍。

評卷參考原圖 · 第 65 頁

學生作答

本小題以圖像作答,請對照下方原稿。

學生原稿裁圖
評分點得分結果
週期減半/頻率加倍1/1已取得
感應電壓振幅加倍0/1未取得

評語與失分分析

新波形頻率加倍正確,振幅仍維持原值,未表示感應電壓加倍。

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

週期減半、頻率加倍;發射電流振幅不變時,磁通改變率加倍,感應電壓振幅亦加倍。

12(c)非金屬背蓋與渦流電和磁 / 電磁感應0/2
因果解釋

題目

手機內置接收線圈,可放在充電板上作無線充電。充電板內置發射線圈,並連接電源。

解釋無線充電手機為何需要非金屬背蓋。

原題插圖

評卷參考

金屬背蓋會產生渦流,導致發熱/能量損耗或削弱磁通。非金屬絕緣背蓋可避免渦流,讓磁場有效穿過。

學生作答

As principle of wirelessly charging is to induce current
thus voltage on a electrical conduction metal i.e. cell.
Thus, non-metallic back covers will not disturb the effect of induction.

學生原稿裁圖
評分點得分結果
指出金屬中產生渦流0/1未取得
指出發熱/能量損耗或削弱磁通0/1未取得

評語與失分分析

未提到渦流及其發熱/阻擋磁通效應,解釋不夠具體。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

金屬背蓋會產生渦流,導致發熱/能量損耗或削弱磁通。非金屬絕緣背蓋可避免渦流,讓磁場有效穿過。

13(a)(i)半衰期與衰變常數放射現象和核能 / 放射衰變2/2
公式與運算

題目

氡(Rn-222)是無色、無臭、無味的放射性氣體,從地下基岩或含花崗岩的混凝土釋出。Rn-222 以半衰期 3.82 日放出 α 粒子而衰變。

氡-222 的半衰期為 3.82 日。求其衰變常數,單位為 s⁻¹。

評卷參考

k = ln 2/(3.82 × 24 × 3600) ≈ 2.10 × 10⁻⁶ s⁻¹。

學生作答

k = ln 2 / (3.82 × 24 × 60 × 60)
= 2.10 × 10⁻⁶ s⁻¹

學生原稿裁圖
評分點得分結果
以秒為單位代入半衰期公式1/1已取得
得到 2.10 × 10⁻⁶ s⁻¹1/1已取得

評語與失分分析

已把日換成秒,衰變常數的公式及數值正確。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

k = ln 2/(3.82 × 24 × 3600) ≈ 2.10 × 10⁻⁶ s⁻¹。

13(a)(ii)活度與原子數放射現象和核能 / 放射衰變1/2
公式與運算待教師校對

題目

氡(Rn-222)是無色、無臭、無味的放射性氣體,從地下基岩或含花崗岩的混凝土釋出。Rn-222 以半衰期 3.82 日放出 α 粒子而衰變。

室內每立方米空氣因氡氣產生的平均活度為 48 Bq。估算每立方米的氡原子數。

評卷參考

N = A/k = 48/(2.10 × 10⁻⁶) ≈ 2.29 × 10⁷ 個。

學生作答

A = k N
N = 48 / k
= 2.29 × 10⁷

學生原稿裁圖
評分點得分結果
運用 N = A/k 的代入0/1未取得
得到 2.29 × 10⁷ 個1/1已取得

評語與失分分析

已寫 A = kN、N = 48/k 並得到正確數值。原判因未重寫 k 的數值扣一分,需校對步驟分。

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。

改善方法與參考寫法

訂正時先核對題目要求,再按以下要點補齊:

N = A/k = 48/(2.10 × 10⁻⁶) ≈ 2.29 × 10⁷ 個。

13(a)(iii)氡氣的內照射危害放射現象和核能 / 放射衰變2/2
因果解釋

題目

氡(Rn-222)是無色、無臭、無味的放射性氣體,從地下基岩或含花崗岩的混凝土釋出。Rn-222 以半衰期 3.82 日放出 α 粒子而衰變。

α 粒子的穿透力有限,解釋為何室內氡氣仍會危害人體。

評卷參考

氡氣可隨呼吸進入肺部;α 粒子電離能力強,可損害附近細胞/組織。

學生作答

As human inhale radon in indoor is difficult to be sense by normal feeling. As if human inhale it, α-particle has strong ionizing power. Thus harmful to body.

學生原稿裁圖
評分點得分結果
指出氡氣可被吸入體內1/1已取得
指出 α 粒子電離能力強,損害細胞1/1已取得

評語與失分分析

已交代吸入氡氣及 α 粒子的強電離能力。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

氡氣可隨呼吸進入肺部;α 粒子電離能力強,可損害附近細胞/組織。

13(b)α、β 衰變序列放射現象和核能 / 放射衰變2/2
圖像表達

題目

Rn-222 屬於以鈾-238(U-238)開始的衰變系列。已知 U-238 依 α、β、β、α 的次序衰變為釷-230(Th-230)。

以箭頭完成 U-238 經 α、β、β、α 衰變至 Th-230 的序列。

原題插圖

評卷參考

U-238 (92,238) → Th-234 (90,234) → Pa-234 (91,234) → U-234 (92,234) → Th-230 (90,230)。依次為 α、β⁻、β⁻、α;本題止於 Th-230。

評卷參考原圖 · 第 66 頁

學生作答

238 92 U, 234 90, 91, 92, 230 90

學生原稿裁圖
評分點得分結果
四段 α、β⁻、β⁻、α 衰變箭頭的方向及位置正確,終點為 Th-2302/2已取得

評語與失分分析

四段 α、β⁻、β⁻、α 衰變箭頭的方向及位置均正確,序列由 U-238 正確連接至 Th-230。

改善方法與參考寫法

可延續本題的作答方法,並用以下要點作最後核對:

U-238 (92,238) → Th-234 (90,234) → Pa-234 (91,234) → U-234 (92,234) → Th-230 (90,230)。依次為 α、β⁻、β⁻、α;本題止於 Th-230。

Student assessment report
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REPORT 01 · PHYSICS · PAPER 1B · 2024

Student Assessment Report

Ethan Chan
5A
5A-17
Physics · Paper 1B

Assessment: 19 Aug 2026 | Report: 29 Sep 2026

Paper score · 60/8471.4%
Assessed13 questions46 subquestions
Paper score71.4%60 / 84 marks
Marks lost24 marksBased on the report score

Paper performanceRates are based on this paper only, not class percentiles or a predicted DSE level.

The score is 60/84 (71.4%). Force and motion is the strongest area. Prioritise heat and gases, and electricity and magnetism, particularly thermal radiation, mass conversion, resistance changes and eddy currents.

Scores by assessed topic

Heat and gases 6/1250.0%
Force and motion 19/2286.4%
Waves 16/2176.2%
Electricity and magnetism 12/2157.1%
Radioactivity and nuclear energy 7/887.5%

Scope: Questions 1–13, worth 84 marks. Items requiring review are marked in the question section.

Knowledge mapEach node maps to one assessed subquestion. Parent totals sum the marks; unassessed content is omitted.

Secure ≥80%Developing 60–<80%Needs attention <60%

Only assessed content is shown. Percentages describe performance on the linked subquestions, not comprehensive mastery of each concept.

Heat and gases6/12 · 50.0%

Temperature, heat and internal energy

Force and motion19/22 · 86.4%
Waves16/21 · 76.2%

Nature of waves

Wave properties of light

Refraction of light

Electricity and magnetism12/21 · 57.1%
Radioactivity and nuclear energy7/8 · 87.5%

Exam skillsSubquestions are grouped into six categories by their main demand, with each assigned once. These are paper-based observations, not additional marks.

Performance by response demand

Response-demand scores25%50%75%100%Reading62.5%Calculation75.9%Explanation65.2%Diagrams80.0%Experiment66.7%Reasoning66.7%

Outer ring: 100% · Integrated reasoning has one subquestion

Reading and judgement 5/862.5%
Formulae and calculation 22/2975.9%
Causal explanation 15/2365.2%
Diagrams and graphs 12/1580.0%
Experimental design 4/666.7%
Integrated reasoning 2/366.7%

Question-by-question review

1(a)Heat transferHeat and gases / Temperature, heat and internal energy1/1
Reading and judgement

Question paper

A bottle of water at 4 °C is taken out of a refrigerator and placed on a table. The room temperature is 30 °C.

State one way of heat transfer from the surroundings to the bottle of water.

Marking reference

conduction / radiation

Student response

Radiation from Sun to bottle

Original student-response crop
Marking pointScoreOutcome
conduction / radiation1/1Awarded

Feedback and mark-loss analysis

Radiation is correctly identified as a heat-transfer mechanism.

Improvement and reference response

Keep this approach and use the following reference for a final check:

conduction / radiation

1(b)Aluminium foil and thermal radiationHeat and gases / Temperature, heat and internal energy0/2
Causal explanation

Question paper

A bottle of water at 4 °C is taken out of a refrigerator and placed on a table. The room temperature is 30 °C.

Explain whether wrapping the bottle with an aluminum foil will speed up the rate of temperature increase.

Marking reference

Will not, as the silvery surface of aluminum foil is a poor radiation absorber / good radiation reflector.

Student response

As Al foil is a good conductor of heat, which speed up the heat transfer from surrounding to bottle

Original student-response crop
Marking pointScoreOutcome
State 'Will not'.0/1Not awarded
Silvery surface of aluminum foil is a poor radiation absorber / good radiation reflector.0/1Not awarded

Feedback and mark-loss analysis

The answer uses thermal conductivity to predict faster warming, overlooking the reflective surface and its low absorption of radiation.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

Will not, as the silvery surface of aluminum foil is a poor radiation absorber / good radiation reflector.

1(c)(i)Source of condensed dropletsHeat and gases / Temperature, heat and internal energy0/1
Reading and judgement

Question paper

A bottle of water at 4 °C is taken out of a refrigerator and placed on a table. The room temperature is 30 °C. After a period of time, water droplets form on the surface of the bottle.

State the source of the water droplets.

Marking reference

The water droplets come from the moisture / water vapour in the air (surroundings).

Student response

air

Original student-response crop
Marking pointScoreOutcome
The water droplets come from the moisture / water vapour in the air (surroundings).0/1Not awarded

Feedback and mark-loss analysis

“Air” is too general: the source must be identified as water vapour or moisture in the air.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

The water droplets come from the moisture / water vapour in the air (surroundings).

1(c)(ii)Latent heat and mass conversionHeat and gases / Temperature, heat and internal energy0/2
Formulae and calculation

Question paper

A bottle of water at 4 °C is taken out of a refrigerator and placed on a table. The room temperature is 30 °C. After a period of time, water droplets form on the surface of the bottle.

Suppose 0.40 g of water droplets are collected on the surface of the bottle. Estimate the latent heat released from these droplets. Given: specific latent heat of vaporization of water = 2.26 x 10^6 J kg^-1

Marking reference

E = (0.40 x 10^-3)(2.26 x 10^6) = 904 J

Student response

E = (0.4)(2.26×10⁶)
= 9.04×10⁵ J

Original student-response crop
Marking pointScoreOutcome
Substitution: E = (0.40 x 10^-3)(2.26 x 10^6)0/1Not awarded
Answer: 904 J0/1Not awarded

Feedback and mark-loss analysis

The mass 0.40 g is used as 0.40 kg, making the calculated energy 1000 times too large.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

E = (0.40 x 10^-3)(2.26 x 10^6) = 904 J

2(a)(i)Mean kinetic energy of atomsHeat and gases / Gases2/2
Formulae and calculation

Question paper

A closed vessel of fixed volume contains argon, a monatomic gas, maintained at temperature T₀. The root-mean-square speed of the argon atoms is 500 m s⁻¹. The mass of an argon atom is 6.63 × 10⁻²⁶ kg.

Calculate the average kinetic energy of the argon atoms, Ek. Given that the mass of an argon atom is 6.63 x 10^-26 kg.

Marking reference

Ek = 1/2 * (6.63 x 10^-26) * (500)^2 = 8.2875 x 10^-21 J ≈ 8.29 x 10^-21 J

Student response

E_k = 1/2 (6.63×10⁻²⁶)(500)²
= 8.29×10⁻²¹ J

Original student-response crop
Marking pointScoreOutcome
Substitution: 1/2 * (6.63 x 10^-26) * (500)^21/1Awarded
Answer: 8.29 x 10^-21 J (Accept: 8.29 ~ 8.30 x 10^-21 J)1/1Awarded

Feedback and mark-loss analysis

The formula, substitution and numerical kinetic energy are correct.

Improvement and reference response

Keep this approach and use the following reference for a final check:

Ek = 1/2 * (6.63 x 10^-26) * (500)^2 = 8.2875 x 10^-21 J ≈ 8.29 x 10^-21 J

2(a)(ii)Kinetic energy and temperatureHeat and gases / Gases1/2
Formulae and calculation

Question paper

A closed vessel of fixed volume contains argon, a monatomic gas, maintained at temperature T₀. The root-mean-square speed of the argon atoms is 500 m s⁻¹. The mass of an argon atom is 6.63 × 10⁻²⁶ kg.

Hence, or otherwise, find T0 (in K).

Marking reference

Ek = 3RT0 / 2NA; T0 = (2/3) * (8.29 x 10^-21 / 8.31) * (6.02 x 10^23) = 400.247 (K) ≈ 400 (K)

Student response

nRT = 1/3 N m c̄²
3/2 R T / N_A = 1/2 m c̄² = E_k
T = 3.65×10⁻¹⁸ K

Original student-response crop
Marking pointScoreOutcome
Substitution into kinetic theory formula using Ek from (a)(i).1/1Awarded
Answer: 400 (K)0/1Not awarded

Feedback and mark-loss analysis

The relationship between kinetic energy and temperature is correct, but the final temperature is implausible. The relationship mark is retained.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

Ek = 3RT0 / 2NA; T0 = (2/3) * (8.29 x 10^-21 / 8.31) * (6.02 x 10^23) = 400.247 (K) ≈ 400 (K)

2(b)RMS speed at constant temperatureHeat and gases / Gases2/2
Causal explanation

Question paper

A closed vessel of fixed volume contains argon, a monatomic gas, maintained at temperature T₀. The root-mean-square speed of the argon atoms is 500 m s⁻¹. The mass of an argon atom is 6.63 × 10⁻²⁶ kg.

If some of the argon has been leaked from the vessel while the temperature remains at T0, state and explain the change, if any, in the root-mean-square speed of the argon atoms inside the vessel.

Marking reference

As temperature remains at T0, Ek remains unchanged / cr.m.s. depends on temperature, so root-mean-square speed cr.m.s. remains unchanged.

Student response

As temperature unchange,
average kinetic energy of argon unchange.
Thus, c_rms also unchange.

Original student-response crop
Marking pointScoreOutcome
State that Ek remains unchanged or cr.m.s. depends on temperature.1/1Awarded
Conclude that root-mean-square speed cr.m.s. remains unchanged.1/1Awarded

Feedback and mark-loss analysis

The explanation correctly links constant temperature to constant mean kinetic energy and unchanged RMS speed.

Improvement and reference response

Keep this approach and use the following reference for a final check:

As temperature remains at T0, Ek remains unchanged / cr.m.s. depends on temperature, so root-mean-square speed cr.m.s. remains unchanged.

3(a)Work and kinetic energyForce and motion / Force and motion2/2
Formulae and calculation

Question paper

A small block P of mass 0.20 kg rests at side A of a horizontal table. The table is smooth from A to B and rough from B to C. A horizontal force of 0.30 N acts as shown in Figure 3.1; AB = 0.75 m. Neglect air resistance.

Find the speed of the block after it travels 0.75 m to point B.

Original question figure

Marking reference

By Fs = 1/2mv^2, 0.30 x 0.75 = 1/2 (0.20) v^2 v = 1.5 m s^-1 (Alternative: v^2 = u^2 + 2as and F = ma)

Student response

WD = F · s
1/2 (0.2) v² = (0.3)(0.75)
v = 1.5 m s⁻¹

Original student-response crop
Marking pointScoreOutcome
Substitution of values into work-energy equation (Fs = 1/2mv^2) or equivalent kinematic/force equations (v^2 = u^2 + 2as and F = ma).1/1Awarded
Final answer v = 1.5 m s^-1 (with correct unit).1/1Awarded

Feedback and mark-loss analysis

The work–energy relationship gives the correct speed of 1.5 m s⁻¹.

Improvement and reference response

Keep this approach and use the following reference for a final check:

By Fs = 1/2mv^2, 0.30 x 0.75 = 1/2 (0.20) v^2 v = 1.5 m s^-1 (Alternative: v^2 = u^2 + 2as and F = ma)

3(b)Free-body diagramForce and motion / Force and motion2/2
Diagrams and graphsTeacher review

Question paper

A small block P of mass 0.20 kg rests at side A of a horizontal table. The table is smooth from A to B and rough from B to C. A horizontal force of 0.30 N acts as shown in Figure 3.1; AB = 0.75 m. Neglect air resistance.

The horizontal force is removed when block P just reaches B. When the block continues to travel from B to C, on the free-body diagram below indicate and name the force(s) acting on the block.

Original question figure
Original question figure

Marking reference

A free-body diagram of block P showing three forces: 1. Normal reaction (upward) 2. Weight (downward) 3. Friction (leftward, opposing motion)

Original marking-scheme figure · page 59

Student response

This response is graphical; refer to the original crop below.

Original student-response crop
Marking pointScoreOutcome
Draw and label the vertical forces: an upward arrow (normal reaction/force) and a downward arrow (weight/gravity).1/1Awarded
Draw and label the horizontal force: a leftward arrow (friction) acting on block P.1/1Awarded

Feedback and mark-loss analysis

The original drawing identifies normal reaction, weight and friction in the required directions.

Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

Improvement and reference response

Keep this approach and use the following reference for a final check:

A free-body diagram of block P showing three forces: 1. Normal reaction (upward) 2. Weight (downward) 3. Friction (leftward, opposing motion)

3(c)Vertical displacement in projectile motionForce and motion / Force and motion2/2
Formulae and calculation

Question paper

A small block P of mass 0.20 kg rests at side A of a horizontal table. The table is smooth from A to B and rough from B to C. A horizontal force of 0.30 N acts as shown in Figure 3.1; AB = 0.75 m. Neglect air resistance.

The block leaves side C of the table and takes 0.35 s to reach point K on the ground. Estimate the height of the table.

Original question figure

Marking reference

Height = 1/2 gt^2 = 1/2 (9.81)(0.35)^2 = 0.6008625 m ≈ 0.601 m Accept: 0.60 m ~ 0.613 m

Student response

s_y = u_y t + 1/2 a_y t²
= 0 + 1/2 (9.81)(0.35)²
∴ height = 0.601 m

Original student-response crop
Marking pointScoreOutcome
Substitution into vertical displacement formula h = 1/2 gt^2 using g ≈ 9.81 and t = 0.35.1/1Awarded
Final answer for height within the range 0.60 m to 0.613 m.1/1Awarded

Feedback and mark-loss analysis

The vertical motion is correctly treated as starting with zero vertical speed, giving the correct height.

Improvement and reference response

Keep this approach and use the following reference for a final check:

Height = 1/2 gt^2 = 1/2 (9.81)(0.35)^2 = 0.6008625 m ≈ 0.601 m Accept: 0.60 m ~ 0.613 m

4(a)(i)Centripetal forceForce and motion / Circular motion2/2
Formulae and calculation

Question paper

A sphere of radius 0.50 m rotates about a vertical axis ACB at a constant angular speed of 6 rad s⁻¹, with C at its centre. A small piece of plasticine P of mass 0.020 kg is stuck to the surface and rotates in a horizontal plane through C.

Find the magnitude of the centripetal force acting on P.

Original question figure

Marking reference

F = mω^2r = 0.020 x 6^2 x 0.50 = 0.36 N

Student response

F_c = m ω² r
= (0.02)(6)²(0.5)
= 0.36 N

Original student-response crop
Marking pointScoreOutcome
Substitution into centripetal force formula F = mω^2r.1/1Awarded
Final answer F = 0.36 N.1/1Awarded

Feedback and mark-loss analysis

The centripetal-force formula, mass conversion and numerical result are correct.

Improvement and reference response

Keep this approach and use the following reference for a final check:

F = mω^2r = 0.020 x 6^2 x 0.50 = 0.36 N

4(a)(ii)Tangential velocity on releaseForce and motion / Circular motion1/1
Diagrams and graphsTeacher review

Question paper

A sphere of radius 0.50 m rotates about a vertical axis ACB at a constant angular speed of 6 rad s⁻¹, with C at its centre. A small piece of plasticine P of mass 0.020 kg is stuck to the surface and rotates in a horizontal plane through C.

The sphere's angular speed is increasing. If P finally leaves the sphere at the position shown in Figure 4.1(b) (Top view from A). Indicate on Figure 4.1(b) the direction of motion of P when it just leaves the sphere.

Original question figure

Marking reference

Draw an arrow from P tangent to the circular path, in the direction of motion (down-left in Figure 4.1(b)). The velocity is not directed towards the centre.

Original marking-scheme figure · page 59

Student response

This response is graphical; refer to the original crop below.

Original student-response crop
Marking pointScoreOutcome
Draw an arrow tangential to the circular path at P, in the direction of release.1/1Awarded

Feedback and mark-loss analysis

The velocity on release is tangential. The arrow on the original script follows the tangent.

Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

Improvement and reference response

Keep this approach and use the following reference for a final check:

Draw an arrow from P tangent to the circular path, in the direction of motion (down-left in Figure 4.1(b)). The velocity is not directed towards the centre.

4(b)(i)Comparing angular speedsForce and motion / Circular motion1/1
Reading and judgement

Question paper

A sphere of radius 0.50 m rotates about a vertical axis ACB at a constant angular speed of 6 rad s⁻¹, with C at its centre. A small piece of plasticine P of mass 0.020 kg is stuck to the surface and rotates in a horizontal plane through C. Another piece of plasticine Q is stuck to the sphere’s surface as shown in Figure 4.2.

State whether P and Q have the same angular speed.

Original question figure

Marking reference

same angular speed

Student response

Yes

Original student-response crop
Marking pointScoreOutcome
State that the angular speed is the same.1/1Awarded

Feedback and mark-loss analysis

The two points on the same rigid body have the same angular speed.

Improvement and reference response

Keep this approach and use the following reference for a final check:

same angular speed

4(b)(ii)Centripetal acceleration and radiusForce and motion / Circular motion2/2
Causal explanation

Question paper

A sphere of radius 0.50 m rotates about a vertical axis ACB at a constant angular speed of 6 rad s⁻¹, with C at its centre. A small piece of plasticine P of mass 0.020 kg is stuck to the surface and rotates in a horizontal plane through C. Another piece of plasticine Q is stuck to the sphere’s surface as shown in Figure 4.2.

Explain whether P and Q have the same magnitude of centripetal acceleration.

Original question figure

Marking reference

different / smaller magnitude of centripetal acceleration (aQ < aP) as Q takes a different / smaller radius (rQ < rP)

Student response

NO. As r_Q < r_P
a_Q < a_P

Original student-response crop
Marking pointScoreOutcome
State that the magnitude of centripetal acceleration is different or smaller (aQ < aP).1/1Awarded
Explain that Q has a smaller radius of rotation (rQ < rP).1/1Awarded

Feedback and mark-loss analysis

The answer correctly identifies the smaller centripetal acceleration at the smaller radius of Q.

Improvement and reference response

Keep this approach and use the following reference for a final check:

different / smaller magnitude of centripetal acceleration (aQ < aP) as Q takes a different / smaller radius (rQ < rP)

5(a)Displacement graph of a sound waveWaves / Nature of waves0/2
Diagrams and graphsTeacher review

Question paper

Figure 5.1 shows the distribution of air particles at an instant in a sound wave produced by a loudspeaker. The wave travels to the right; P, Q, R, S and T are the marked regions.

Sketch the displacement-distance graph of the air particles at that instant in the grid provided. Take the displacement to the right as positive (+).

Original question figure
Original question figure

Marking reference

Displacement is zero at the centres of compression and rarefaction (P, R, T), with opposite displacement extrema at Q and S. Starting at P, the curve first moves below the axis, reaches its first trough at Q, crosses zero at R, and reaches a crest at S.

Original marking-scheme figure · page 60

Student response

This response is graphical; refer to the original crop below.

Original student-response crop
Marking pointScoreOutcome
Correct zero-displacement starting position and initial direction.0/1Not awarded
Correct phase, wavelength and positions of zero displacement and extrema.0/1Not awarded

Feedback and mark-loss analysis

The starting displacement and phase do not match the particle distribution. Particle density must not be copied directly as displacement.

Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

Displacement is zero at the centres of compression and rarefaction (P, R, T), with opposite displacement extrema at Q and S. Starting at P, the curve first moves below the axis, reaches its first trough at Q, crosses zero at R, and reaches a crest at S.

5(b)(i)Maximum particle speedWaves / Nature of waves0/1
Reading and judgementTeacher review

Question paper

Figure 5.1 shows the distribution of air particles at an instant in a sound wave produced by a loudspeaker. The wave travels to the right; P, Q, R, S and T are the marked regions.

At the instant shown, state a region (P, Q, R, S or T) in which the air particles are moving with the highest speed.

Original question figure

Marking reference

P / R / T

Student response

P , R , T

Original student-response crop
Marking pointScoreOutcome
Identify any one of the points P, R, or T (the peaks or troughs).0/1Not awarded

Feedback and mark-loss analysis

The answer lists P, R and T, all of which appear in the reference. The original system awarded 0/1 for listing multiple regions; this decision is retained for teacher review.

Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

P / R / T

5(b)(ii)Region of minimum pressureWaves / Nature of waves1/1
Reading and judgement

Question paper

Figure 5.1 shows the distribution of air particles at an instant in a sound wave produced by a loudspeaker. The wave travels to the right; P, Q, R, S and T are the marked regions.

At the instant shown, state a region (P, Q, R, S or T) in which the air pressure is the lowest.

Original question figure

Marking reference

R: the rarefaction region has the lowest air pressure.

Student response

R

Original student-response crop
Marking pointScoreOutcome
Identify R as the region of minimum air pressure.1/1Awarded

Feedback and mark-loss analysis

R is correctly selected as the rarefaction region with minimum pressure.

Improvement and reference response

Keep this approach and use the following reference for a final check:

R: the rarefaction region has the lowest air pressure.

6(a)Diffraction-grating spacingWaves / Wave properties of light3/3
Formulae and calculation

Question paper

After removing a CD’s protective coating and reflective layer, the CD becomes a diffraction grating with evenly spaced parallel slits [Figure 6.1(a)]. The laser set-up in Figure 6.1(b) measures the slit separation d. The grating–screen separation is L = 0.10 m, the separation between the first-order maxima is x = 0.092 m, and the red laser wavelength is λ = 650 nm.

Estimate d.

Original question figure

Marking reference

Apply d sin θ = mλ. tan θ = (x/2) / L => θ = 24.702430° or sin θ = (x/2) / sqrt(L^2 + (x/2)^2) = 0.417906. d = λ / sin θ = (650 x 10^-9) / 0.418 = 1.555375 x 10^-6 m ≈ 1.56 μm.

Student response

d sin θ = n λ
d sin ( tan⁻¹ ( 0.092/2 / 0.1 ) ) = (1)(650 × 10⁻⁹)
d = 1.56 × 10⁻⁶ m

Original student-response crop
Marking pointScoreOutcome
Correct substitution or calculation to find the angle θ (e.g., using tan θ = (x/2)/L or sin θ calculation).1/1Awarded
Correct substitution into the diffraction grating formula d sin θ = mλ (where m=1).1/1Awarded
Final answer for d ≈ 1.56 μm (Accept: 1.56 μm ~ 1.6 μm).1/1Awarded

Feedback and mark-loss analysis

The diffraction angle is obtained from the tangent relation and used correctly in the grating equation.

Improvement and reference response

Keep this approach and use the following reference for a final check:

Apply d sin θ = mλ. tan θ = (x/2) / L => θ = 24.702430° or sin θ = (x/2) / sqrt(L^2 + (x/2)^2) = 0.417906. d = λ / sin θ = (650 x 10^-9) / 0.418 = 1.555375 x 10^-6 m ≈ 1.56 μm.

6(b)Wavelength and fringe separationWaves / Wave properties of light2/2
Causal explanation

Question paper

After removing a CD’s protective coating and reflective layer, the CD becomes a diffraction grating with evenly spaced parallel slits [Figure 6.1(a)]. The laser set-up in Figure 6.1(b) measures the slit separation d. The grating–screen separation is L = 0.10 m, the separation between the first-order maxima is x = 0.092 m, and the red laser wavelength is λ = 650 nm.

State and explain the change in x if green laser light is used.

Original question figure

Marking reference

x will decrease as λ decreases, sin θ and θ will decrease.

Student response

Decrease .
As green laser has shorter wavelength, sin θ reduce
θ reduce . Thus x reduce .

Original student-response crop
Marking pointScoreOutcome
State that x will decrease.1/1Awarded
Explain that as λ decreases, sin θ (and thus θ) will decrease according to the diffraction formula.1/1Awarded

Feedback and mark-loss analysis

The explanation correctly links shorter wavelength to a smaller diffraction angle and reduced separation.

Improvement and reference response

Keep this approach and use the following reference for a final check:

x will decrease as λ decreases, sin θ and θ will decrease.

7(a)Air temperature and sound speedWaves / Sound1/1
Reading and judgement

Question paper

Figure 7.1 shows the speed of sound at different air temperatures.

With reference to the graph, state the relationship between the speed of sound and the air temperature.

Original question figure

Marking reference

The speed of sound increases (linearly) with air temperature. / The higher the air temperature, the greater is the speed of sound.

Student response

Speed of sound increase when air temperature increase.

Original student-response crop
Marking pointScoreOutcome
State that the speed of sound increases with air temperature.1/1Awarded

Feedback and mark-loss analysis

The graph is correctly read as showing increased sound speed at higher temperature.

Improvement and reference response

Keep this approach and use the following reference for a final check:

The speed of sound increases (linearly) with air temperature. / The higher the air temperature, the greater is the speed of sound.

7(b)Refraction through air layersWaves / Sound2/2
Causal explanation

Question paper

At night the ground cools. Figure 7.2 shows sound travelling from a distant tower clock to an observer.

How does the temperature difference between air layers above the ground explain the situation in Figure 7.2?

Original question figure

Marking reference

The air near the ground is cooler while the air layers higher above are relatively warmer, the sound wave bends downward (towards the normal) as it travels slower when going from a higher temperature (upper) layer into a low temperature (lower) layer and vice versa, i.e. refraction occurs.

Student response

Temperature decrease from sky to ground uniformly.
As sound travel from fast region to slow region, it bends toward to normal of air layers.
Thus, sound moves toward ground.

Original student-response crop
Original student-response crop
Marking pointScoreOutcome
Identify that air near the ground is cooler than air layers higher above.1/1Awarded
Explain that sound bends downward (refraction) because it travels slower in the cooler lower layer.1/1Awarded

Feedback and mark-loss analysis

The answer identifies warmer air above cooler air and explains the downward refraction of sound.

Improvement and reference response

Keep this approach and use the following reference for a final check:

The air near the ground is cooler while the air layers higher above are relatively warmer, the sound wave bends downward (towards the normal) as it travels slower when going from a higher temperature (upper) layer into a low temperature (lower) layer and vice versa, i.e. refraction occurs.

7(c)(i)Ratio of light speed to sound speedWaves / Sound0/1
Formulae and calculation

Question paper

Figure 7.1 shows the speed of sound at different air temperatures. The air temperature is 10 °C. Refer to Figure 7.1.

Estimate the ratio of speed of light to the speed of sound; c/v.

Original question figure

Marking reference

Speed ratio = (3.00 x 10^8) / 337 = 8.90208 x 10^5 ≈ 8.90 x 10^5

Student response

[Crossed out: c / v]

c / v = (3 × 10⁸) / 337
= 8.90 × 10⁶

Original student-response crop
Marking pointScoreOutcome
Correct calculation of the ratio of speed of light to speed of sound (approx 8.90 x 10^5).0/1Not awarded

Feedback and mark-loss analysis

The division is set up correctly, but the exponent in the final answer is one power of ten too large.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

Speed ratio = (3.00 x 10^8) / 337 = 8.90208 x 10^5 ≈ 8.90 x 10^5

7(c)(ii)Distance to a thunderstormWaves / Sound1/2
Formulae and calculationTeacher review

Question paper

Figure 7.1 shows the speed of sound at different air temperatures. The air temperature is 10 °C. Refer to Figure 7.1.

Estimate the distance of a thunderstorm from an observer O if thunder is heard 3.0 s after lightning is seen by O.

Original question figure

Marking reference

Distance = 337 x 3.0 = 1011 m. Accept: 1010 m ~ 1011 m. e.c.f. from (c)(i) using incorrect sound speed.

Student response

⇒ [Crossed out: d = c · t]
[Crossed out: d = v · (t + 3)]

[Crossed out: 1 = c/v · t / (t + 3)]

[Crossed out: v/c t + v/c · 3 = t]

t = 3.37 × 10⁻⁶ s

∴ d = c · t = 1010 m

Original student-response crop
Marking pointScoreOutcome
Substitution: Multiply sound speed by time (337 x 3.0).0/1Not awarded
Final answer: 1011 m (Accept 1010 m ~ 1011 m).1/1Awarded

Feedback and mark-loss analysis

The alternative calculation uses light-travel time and gives 1010 m. The original system awarded only the answer mark; the method mark needs review against the crossed-out working.

Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

Distance = 337 x 3.0 = 1011 m. Accept: 1010 m ~ 1011 m. e.c.f. from (c)(i) using incorrect sound speed.

8(a)Refraction and a virtual imageWaves / Refraction of light2/2
Diagrams and graphsTeacher review

Question paper

Figure 8.1 shows a pencil in a glass of water viewed vertically downwards by an observer. The refractive index of water is 1.33. Rays P and Q come from the pencil tip O, with Q along the vertical. The diagram is not drawn to scale.

On Figure 8.1, complete the paths of these light rays and indicate the image of O seen by the observer (label this as I).

Original question figure

Marking reference

MS diagram shows two rays originating from point O at the bottom of the pencil in water. Upon reaching the water-air interface, they refract away from the normal. The refracted rays are traced back (dashed lines) to intersect at point I, which is higher than O. A vertical dashed line connects O and I. The distance from the water surface to O is labeled 0.10 m.

Original marking-scheme figure · page 61

Student response

This response is graphical; refer to the original crop below.

Original student-response crop
Marking pointScoreOutcome
Draw two rays from O refracting away from the normal at the water surface.1/1Awarded
Correct location of image I formed by the intersection of the two back-projected refracted rays.1/1Awarded

Feedback and mark-loss analysis

The refracted rays and virtual image are present. The original system flagged image legibility for checking.

Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

Improvement and reference response

Keep this approach and use the following reference for a final check:

MS diagram shows two rays originating from point O at the bottom of the pencil in water. Upon reaching the water-air interface, they refract away from the normal. The refracted rays are traced back (dashed lines) to intersect at point I, which is higher than O. A vertical dashed line connects O and I. The distance from the water surface to O is labeled 0.10 m.

8(b)Angle of refractionWaves / Refraction of light2/2
Formulae and calculation

Question paper

Figure 8.1 shows a pencil in a glass of water viewed vertically downwards by an observer. The refractive index of water is 1.33. Rays P and Q come from the pencil tip O, with Q along the vertical. The diagram is not drawn to scale.

The angle between ray P and ray Q is 1.5°. Find the angle of refraction of ray P.

Original question figure

Marking reference

1.33 = sin r / sin 1.5°; r = 1.995175° ≈ 2.00°

Student response

1 sin θ = 1.33 sin 1.5°
θ = 2.00°

Original student-response crop
Marking pointScoreOutcome
Substitution into Snell's Law: 1.33 = sin r / sin 1.5°.1/1Awarded
Final answer: r ≈ 2.00°.1/1Awarded

Feedback and mark-loss analysis

Snell’s law is correctly applied to obtain the angle of refraction.

Improvement and reference response

Keep this approach and use the following reference for a final check:

1.33 = sin r / sin 1.5°; r = 1.995175° ≈ 2.00°

8(c)Apparent depthWaves / Refraction of light2/2
Formulae and calculation

Question paper

Figure 8.1 shows a pencil in a glass of water viewed vertically downwards by an observer. The refractive index of water is 1.33. Rays P and Q come from the pencil tip O, with Q along the vertical. The diagram is not drawn to scale.

Hence, or otherwise, find the distance between image I and the water surface if the depth of water is 0.10 m.

Original question figure

Marking reference

h1 / h = tan 1.5° / tan 2.00° = 0.751681 (or tan 1.5° = PQ/0.10 & tan 2° = PQ/h1); h1 ≈ 0.075 m (i.e. 7.5 cm). Accept: real depth / apparent depth = n.

Student response

⇒ PQ = 0.1 tan 1.5°
[Crossed out: tan(2.00°) = PQ / d_req.]

d_req. = (0.1 tan 1.5°) / tan(2.00°)
d = 0.0752 m

Original student-response crop
Marking pointScoreOutcome
Method: Use of tan ratios or the apparent depth formula (h/h' = n) with explicit steps shown.1/1Awarded
Final answer: h1 ≈ 0.075 m or 7.5 cm.1/1Awarded

Feedback and mark-loss analysis

The trigonometric relationship gives the correct apparent depth.

Improvement and reference response

Keep this approach and use the following reference for a final check:

h1 / h = tan 1.5° / tan 2.00° = 0.751681 (or tan 1.5° = PQ/0.10 & tan 2° = PQ/h1); h1 ≈ 0.075 m (i.e. 7.5 cm). Accept: real depth / apparent depth = n.

9(a)Distribution of induced chargesElectricity and magnetism / Electrostatics2/2
Diagrams and graphsTeacher review

Question paper

Figure 9.1 shows two identical conducting light spheres P and Q placed close together without touching, on insulating stands. Both are initially uncharged. A negatively charged plastic rod is brought close to Q without touching it.

On Figure 9.1, sketch the distribution of charges on P and on Q.

Original question figure

Marking reference

Both spheres are polarised: show negative charges on the left and positive charges on the right of each sphere, as in the reference figure. Neither sphere touches the other or the rod.

Original marking-scheme figure · page 62

Student response

This response is graphical; refer to the original crop below.

Original student-response crop
Marking pointScoreOutcome
Correct distribution of charges on sphere Q: positive charges (+) on the right side (near the rod) and negative charges (-) on the left side.1/1Awarded
Correct distribution of charges on sphere P: positive charges (+) on the right side (near Q) and negative charges (-) on the left side.1/1Awarded

Feedback and mark-loss analysis

The original system awarded full credit, but the charge symbols should be checked against the crop because legibility was flagged.

Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

Improvement and reference response

Keep this approach and use the following reference for a final check:

Both spheres are polarised: show negative charges on the left and positive charges on the right of each sphere, as in the reference figure. Neither sphere touches the other or the rod.

9(b)Charge conservation on the rodElectricity and magnetism / Electrostatics1/2
Causal explanation

Question paper

Figure 9.1 shows two identical conducting light spheres P and Q placed close together without touching, on insulating stands. Both are initially uncharged. A negatively charged plastic rod is brought close to Q without touching it. While the plastic rod remains in the position shown, a student touches P momentarily with a finger. The plastic rod is removed afterwards.

Explain whether the amount of charges on the plastic rod would decrease.

Original question figure

Marking reference

No, it remains unchanged as charging is through induction (without any contact or transfer of charges).

Student response

No. As plastic rod doesn't earthed.

Original student-response crop
Marking pointScoreOutcome
State that the charge remains unchanged / No.1/1Awarded
Reason: charging is through induction / without any contact or transfer of charges.0/1Not awarded

Feedback and mark-loss analysis

The unchanged charge is correctly identified, but “not earthed” does not establish the absence of charge transfer.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

No, it remains unchanged as charging is through induction (without any contact or transfer of charges).

9(c)Identifying an unknown chargeElectricity and magnetism / Electrostatics1/2
Experimental design

Question paper

Figure 9.1 shows two identical conducting light spheres P and Q placed close together without touching, on insulating stands. Both are initially uncharged. A negatively charged plastic rod is brought close to Q without touching it. While the plastic rod remains in the position shown, a student touches P momentarily with a finger. The plastic rod is removed afterwards.

The two light spheres are now suspended by nylon threads from fixed supports such that the spheres are far apart from each other. Explain how you would use one of the spheres to test for the unknown polarity of another charged rod.

Original question figure

Marking reference

Hold / bring the unknown charged rod near sphere P (which carries positive charges) without touching it. If P is repelled, the rod is positive. If P is attracted, the rod is negative.

Student response

By previous action, P is positively charged and Q is neutral.
Thus, use P.
If the rod is positive, P repulse. If rod is negative P attracted.

Original student-response crop
Marking pointScoreOutcome
Procedure: Hold / bring the unknown charged rod near sphere P (carrying positive charges) without touching it.0/1Not awarded
Observation/Conclusion: If P is repelled, the rod is positive; OR if P is attracted, the rod is negative.1/1Awarded

Feedback and mark-loss analysis

The attraction and repulsion deductions are correct; the procedure should specify bringing the rod near without touching.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

Hold / bring the unknown charged rod near sphere P (which carries positive charges) without touching it. If P is repelled, the rod is positive. If P is attracted, the rod is negative.

10(a)Energy-conservation experimentForce and motion / Work, energy and momentum3/4
Experimental designTeacher review

Question paper

In Figure 10.1, one end of an inextensible string is attached to a small metal ball and its upper end O is fixed to a stand. A protractor is fixed to the stand behind the string.

Write down the steps that you would take to demonstrate the conservation of energy using the set-up given.

Original question figure

Marking reference

1. Use protractor to mark a specific measurable angle. 2. Release ball from rest with string taut. 3. Measure angle at highest point on the other side (or observe if it swings back to original position). 4. Compare initial and final angles; equality implies conservation of mechanical energy.

Student response

Place the small metal ball at 0° of protractor with the string straight.
Release the ball and record the maximum degree that ball can reach at another side of protractor.
Repeat the experiment at different degree.

Note that ball must reach the other side with same degree (i.e. degree ) as released.

Thus, Potential energy of ball is conserved.

Original student-response crop
Marking pointScoreOutcome
Use the protractor to measure or mark a specific angle at which the ball is released (measurable and recorded).0/1Not awarded
Hold the ball at the marked angle and release it from rest with the string taut.1/1Awarded
Measure the angle at which the ball reaches its highest point (or observe if it swings back to original position).1/1Awarded
Compare initial and final angles; equality implies total mechanical energy is conserved.1/1Awarded

Feedback and mark-loss analysis

Release, measurement of the opposite angle and comparison are described. The initial non-zero release angle is insufficiently specified.

Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

1. Use protractor to mark a specific measurable angle. 2. Release ball from rest with string taut. 3. Measure angle at highest point on the other side (or observe if it swings back to original position). 4. Compare initial and final angles; equality implies conservation of mechanical energy.

10(b)(i)(I)Momentum along the collision directionForce and motion / Work, energy and momentum1/1
Causal explanation

Question paper

The Newton’s cradle in Figure 10.2 consists of five identical metal spheres suspended in a row by equal-length, inextensible light strings from a fixed horizontal support. A and B are displaced slightly to the left together and released from rest. Just after collision, A and B stop while D and E swing slightly to the right together. Neglect air resistance.

Even though the tensions in the strings acting on the spheres are external forces, explain why the law of conservation of momentum can still be applied for this collision.

Original question figure

Marking reference

The tension forces are vertical / perpendicular to the direction of collision, so no external forces act along the colliding / horizontal direction, allowing the law of conservation of momentum to be applied. (Or: tensions are balanced by weights, net force is zero).

Student response

As the direction of tension and the direction of collision is perpendicular to each other.

Original student-response crop
Marking pointScoreOutcome
Explain that tension is perpendicular to the horizontal motion (no external horizontal force) OR net force on the system is zero (tensions balanced by weights).1/1Awarded

Feedback and mark-loss analysis

The answer correctly states that tension is perpendicular to the collision direction.

Improvement and reference response

Keep this approach and use the following reference for a final check:

The tension forces are vertical / perpendicular to the direction of collision, so no external forces act along the colliding / horizontal direction, allowing the law of conservation of momentum to be applied. (Or: tensions are balanced by weights, net force is zero).

10(b)(i)(II)Energy test for Newton’s cradleForce and motion / Work, energy and momentum2/3
Integrated reasoning

Question paper

The Newton’s cradle in Figure 10.2 consists of five identical metal spheres suspended in a row by equal-length, inextensible light strings from a fixed horizontal support. A and B are displaced slightly to the left together and released from rest. Just after collision, A and B stop while D and E swing slightly to the right together. Neglect air resistance.

Suppose that only one sphere (E) swings to the right with speed vE just after collision. By finding vE and hence explain why it is not possible for only one sphere to swing to the right. Given that the speed of sphere A and B just before collision is 0.50 m s^-1. The mass of each sphere is 0.020 kg.

Original question figure

Marking reference

By conservation of momentum, vE = 1.0 m/s. Final KE = 0.01 J. Initial KE = 0.005 J. Since final KE > initial KE, it is not possible.

Student response

p_AB = p_E
(0.02 × 2)(0.5) = (0.02) v_E
v_E = 1 m s⁻¹

KE_AB = ½ (0.02 × 2)(0.5)² = 5 × 10⁻³ J
KE_E = ½ (0.02)(1)² = 0.01 J ≠ KE_AB
if only one ball out, energy of system does not conserved.

Original student-response crop
Marking pointScoreOutcome
Calculate final velocity using conservation of momentum: vE = 2 * 0.50 = 1.0 m/s.1/1Awarded
Calculate final KE (0.01 J) and compare with initial KE (0.005 J).1/1Awarded
Conclude that final KE > initial KE, which is impossible.0/1Not awarded

Feedback and mark-loss analysis

The momentum and energy calculations are correct. The conclusion should explicitly state that the proposed final energy is greater than the initial energy.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

By conservation of momentum, vE = 1.0 m/s. Final KE = 0.01 J. Initial KE = 0.005 J. Since final KE > initial KE, it is not possible.

10(b)(ii)Elasticity of collisionsForce and motion / Work, energy and momentum1/2
Causal explanation

Question paper

The Newton’s cradle in Figure 10.2 consists of five identical metal spheres suspended in a row by equal-length, inextensible light strings from a fixed horizontal support. A and B are displaced slightly to the left together and released from rest. Just after collision, A and B stop while D and E swing slightly to the right together. Neglect air resistance.

The collision repeats alternately from either side for a period of time before the system eventually returns to a rest. Discuss whether the collisions are perfectly elastic.

Original question figure

Marking reference

Not perfectly elastic as some kinetic energy is lost as sound / thermal energy, so total kinetic energy is not conserved.

Student response

No. As external force act on the system (i.e. air resistance) then eventually returns to rest.

Original student-response crop
Marking pointScoreOutcome
State that the collision is not perfectly elastic.1/1Awarded
Reason: kinetic energy is lost as sound / thermal energy (KE not conserved).0/1Not awarded

Feedback and mark-loss analysis

The collision is correctly identified as not perfectly elastic. Air resistance alone does not explain energy conversion during the collision.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

Not perfectly elastic as some kinetic energy is lost as sound / thermal energy, so total kinetic energy is not conserved.

11(a)Resistance of stretched foilElectricity and magnetism / Resistance and circuits0/2
Causal explanationTeacher review

Question paper

Read the following information about deformation sensors. Figure 11.1(a) shows a simple sensing device made of thin, flat rectangular metal foil attached to a plastic backing plate. When the foil, of length l and width w, is stretched as in Figure 11.1(b), its resistance changes. Connected to a suitable circuit, the device monitors deformation through changes in circuit parameters such as voltage.

Referring to Figure 11.1(a) and (b), state and explain how the metal foil's resistance across XY changes when the foil is stretched. Assume that the thickness and resistivity of the foil remain unchanged.

Original question figure

Marking reference

As the foil becomes longer / l increases while its cross-sectional area becomes smaller / A decreases due to decrease in width w, its resistance would increase according to R = ρl/A.

Student response

[Crossed out: R = ρ l / A]

R ∝ l
When foil is stretched, length XY increase.
∴ Resistance increase.

Original student-response crop
Marking pointScoreOutcome
State that the foil becomes longer (l increases) and the cross-sectional area becomes smaller (A decreases) due to decrease in width w.0/1Not awarded
State that resistance increases according to the relation R = ρl/A.0/1Not awarded

Feedback and mark-loss analysis

Increasing length and resistance are stated, but decreasing cross-sectional area is omitted. Partial credit within the original 0/2 needs checking.

Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

As the foil becomes longer / l increases while its cross-sectional area becomes smaller / A decreases due to decrease in width w, its resistance would increase according to R = ρl/A.

11(b)(i)Voltage across a series branchElectricity and magnetism / Resistance and circuits1/1
Formulae and calculation

Question paper

The circuit in Figure 11.2 has four resistors R₁, R₂, R₃ and R₄ connected to an input voltage Vᵢₙ. Vₒᵤₜ is the voltage across DB.

Current I1 flows through branch ABC. Write an equation relating Vin, I1, R1 and R2.

Original question figure

Marking reference

Vin = I1(R1 + R2)

Student response

V_in = I₁ (R₁ + R₂)

Original student-response crop
Marking pointScoreOutcome
Correct expression for Vin in terms of I1, R1, and R2.1/1Awarded

Feedback and mark-loss analysis

The voltage equation for the series branch is correct.

Improvement and reference response

Keep this approach and use the following reference for a final check:

Vin = I1(R1 + R2)

11(b)(ii)Percentage change in bridge outputElectricity and magnetism / Resistance and circuits1/2
Formulae and calculation

Question paper

The circuit in Figure 11.2 has four resistors R₁, R₂, R₃ and R₄ connected to an input voltage Vᵢₙ. Vₒᵤₜ is the voltage across DB.

R4 in the circuit is the sensing device described in the passage, with unstretched resistance 500 Ω. Find the corresponding percentage change in Vout/Vin when R4 increases 0.2% (i.e. becomes 501 Ω). Given: Vout/Vin = R4/(R3+R4) - R2/(R1+R2); R1 = R2 = R3 = 470 Ω.

Original question figure

Marking reference

Before: Vout/Vin = R4/(R3+R4) - R2/(R1+R2) = 500/(470+500) - 470/(470+470) = 0.0154639. After: Vout/Vin = 501/(470+501) - 470/(470+470) = 0.0159629. Percentage increase ≈ 3.23%.

Student response

( V_out / V_in )' = 501 / (470 + 501) - 470 / (470 + 470)

V_out / V_in = 500 / (470 + 500) - 470 / (470 + 470)

% Δ V_out / V_in = [ ( V_out / V_in )' - V_out / V_in ] / ( V_out / V_in ) × 100%
= 0.0972%

Original student-response crop
Marking pointScoreOutcome
Substitution of values into the potential divider/bridge ratio formula for both 'before' and 'after' states.1/1Awarded
Calculate the percentage increase as approximately 3.23% (Accept range 3.2 to 3.23%).0/1Not awarded

Feedback and mark-loss analysis

The before-and-after voltage ratios are set up correctly, but the calculated percentage change is wrong.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

Before: Vout/Vin = R4/(R3+R4) - R2/(R1+R2) = 500/(470+500) - 470/(470+470) = 0.0154639. After: Vout/Vin = 501/(470+501) - 470/(470+470) = 0.0159629. Percentage increase ≈ 3.23%.

11(b)(iii)(I)Identifying the growing crackElectricity and magnetism / Resistance and circuits1/1
Reading and judgement

Question paper

Sensors S₁, S₂, S₃ and S₄, connected to a suitable circuit, are attached to ceiling ABCD as in Figure 11.3 to monitor cracks ①, ② and ③. After a few weeks, the detected deformation is in the order S₁ > S₂ > S₃ > S₄.

Deduce which crack (1, 2 or 3) has grown the most.

Original question figure

Marking reference

crack ①

Student response

①

Original student-response crop
Marking pointScoreOutcome
Identify crack ① as the cause.1/1Awarded

Feedback and mark-loss analysis

Crack ① is correctly identified.

Improvement and reference response

Keep this approach and use the following reference for a final check:

crack ①

11(b)(iii)(II)Direction of stretchingElectricity and magnetism / Resistance and circuits0/1
Reading and judgement

Question paper

Sensors S₁, S₂, S₃ and S₄, connected to a suitable circuit, are attached to ceiling ABCD as in Figure 11.3 to monitor cracks ①, ② and ③. After a few weeks, the detected deformation is in the order S₁ > S₂ > S₃ > S₄.

Deduce the most probable stretching direction (AB, BC or AC) along the ceiling.

Original question figure

Marking reference

along AB

Student response

AC

Original student-response crop
Marking pointScoreOutcome
Identify the direction as along AB.0/1Not awarded

Feedback and mark-loss analysis

The selected direction AC does not match the reference direction AB.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

along AB

12(a)Field of a circular coilElectricity and magnetism / Electromagnetic induction2/2
Diagrams and graphsTeacher review

Question paper

Figure 12.1 shows a coil of several turns carrying a current I in the direction shown.

Sketch the magnetic field pattern produced by the coil when it carries a current I as shown.

Original question figure

Marking reference

Show the magnetic field pattern through the coil, with arrows downwards as in the reference figure. The marking scheme also accepts upward arrows for a different interpretation of the current direction; award for the correct direction and the correct field pattern.

Original marking-scheme figure · page 65

Student response

This response is graphical; refer to the original crop below.

Original student-response crop
Marking pointScoreOutcome
Correct field pattern: closed loops around the coil wires and lines passing through the center of the coil.1/1Awarded
Correct direction: arrows on field lines point downwards through the center of the coil (also accept field lines pointing upwards for observers with different perception of current direction).1/1Awarded

Feedback and mark-loss analysis

The field-line pattern and direction through the centre receive both marks.

Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

Improvement and reference response

Keep this approach and use the following reference for a final check:

Show the magnetic field pattern through the coil, with arrows downwards as in the reference figure. The marking scheme also accepts upward arrows for a different interpretation of the current direction; award for the correct direction and the correct field pattern.

12(b)(i)Induced voltage in the receiverElectricity and magnetism / Electromagnetic induction2/2
Causal explanation

Question paper

In Figure 12.2(a), the coil is connected to an a.c. source as transmitter coil T. A receiver coil R connected to a cathode-ray oscilloscope (CRO) is placed directly above T. Figure 12.2(b) displays the time variation of R’s voltage.

Explain how the voltage of the receiver coil R is produced.

Original question figure

Marking reference

The a.c. flowing in transmitter coil T generates a changing magnetic field, thus by electromagnetic induction an induced e.m.f. is produced in receiver coil R to oppose the changing magnetic flux experienced by it.

Student response

As coil T is connected to an a.c., current is induced in coil R due to changing of B-field from T.
Thus, voltage is induced in R.

Original student-response crop
Marking pointScoreOutcome
The a.c. flowing in transmitter coil T generates a changing magnetic field.1/1Awarded
By electromagnetic induction, an induced e.m.f. is produced in receiver coil R to oppose the changing magnetic flux.1/1Awarded

Feedback and mark-loss analysis

The explanation links alternating current to changing magnetic flux and induced voltage in the receiving coil.

Improvement and reference response

Keep this approach and use the following reference for a final check:

The a.c. flowing in transmitter coil T generates a changing magnetic field, thus by electromagnetic induction an induced e.m.f. is produced in receiver coil R to oppose the changing magnetic flux experienced by it.

12(b)(ii)Waveform after doubling frequencyElectricity and magnetism / Electromagnetic induction1/2
Diagrams and graphsTeacher review

Question paper

In Figure 12.2(a), the coil is connected to an a.c. source as transmitter coil T. A receiver coil R connected to a cathode-ray oscilloscope (CRO) is placed directly above T. Figure 12.2(b) displays the time variation of R’s voltage.

On Figure 12.2(b), sketch the CRO display when the frequency of the a.c. source is doubled.

Original question figure

Marking reference

The period is halved (frequency doubled). With unchanged transmitter-current amplitude, the induced-voltage amplitude doubles because the rate of change of magnetic flux doubles.

Original marking-scheme figure · page 65

Student response

This response is graphical; refer to the original crop below.

Original student-response crop
Marking pointScoreOutcome
Correct frequency: the wave shows double the frequency (frequency doubled).1/1Awarded
Correct amplitude: the wave shows the correct amplitude relative to the original signal.0/1Not awarded

Feedback and mark-loss analysis

The frequency is correctly doubled, but the amplitude is unchanged rather than doubled.

Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

The period is halved (frequency doubled). With unchanged transmitter-current amplitude, the induced-voltage amplitude doubles because the rate of change of magnetic flux doubles.

12(c)Non-metallic covers and eddy currentsElectricity and magnetism / Electromagnetic induction0/2
Causal explanation

Question paper

A mobile phone with a receiver coil inside can be charged wirelessly on a charging pad containing a transmitter coil connected to a power source.

Explain why wirelessly charging of phones need phone cases with non-metallic back covers.

Original question figure

Marking reference

If the back cover is metallic, eddy currents will be produced (by induction), loss of energy / heating effect results / magnetic field / flux is blocked by the metal case and thus making wireless charging impossible. OR Non-metallic materials such as glass are insulators, and no eddy currents are produced. As a result, energy loss / heating effect will be minimized / the magnetic field can pass through the back cover easily.

Student response

As principle of wirelessly charging is to induce current
thus voltage on a electrical conduction metal i.e. cell.
Thus, non-metallic back covers will not disturb the effect of induction.

Original student-response crop
Marking pointScoreOutcome
Metallic cover leads to eddy currents (by induction) OR Non-metallic materials (glass) are insulators and no eddy currents are produced.0/1Not awarded
Eddy currents cause energy loss/heating/blocking of flux making charging impossible OR lack of eddy currents minimizes energy loss and allows magnetic field to pass.0/1Not awarded

Feedback and mark-loss analysis

The explanation does not identify eddy currents and their heating or magnetic-shielding effects.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

If the back cover is metallic, eddy currents will be produced (by induction), loss of energy / heating effect results / magnetic field / flux is blocked by the metal case and thus making wireless charging impossible. OR Non-metallic materials such as glass are insulators, and no eddy currents are produced. As a result, energy loss / heating effect will be minimized / the magnetic field can pass through the back cover easily.

13(a)(i)Half-life and decay constantRadioactivity and nuclear energy / Radioactive decay2/2
Formulae and calculation

Question paper

Radon (Rn-222) is a radioactive gas with no colour, smell or taste, released from underground bedrock or concrete containing granite. It decays by emitting α particles with a half-life of 3.82 days.

Find the decay constant (unit: s^-1) of Rn-222.

Marking reference

k = ln 2 / t_{1/2} = ln 2 / (3.82 * 24 * 3600) = 2.10 * 10^-6 s^-1

Student response

k = ln 2 / (3.82 × 24 × 60 × 60)
= 2.10 × 10⁻⁶ s⁻¹

Original student-response crop
Marking pointScoreOutcome
Substitution: k = ln 2 / (3.82 * 24 * 3600)1/1Awarded
Answer: 2.10 * 10^-6 s^-1 (accept 2.1001405 * 10^-6)1/1Awarded

Feedback and mark-loss analysis

The half-life is converted from days to seconds and used correctly.

Improvement and reference response

Keep this approach and use the following reference for a final check:

k = ln 2 / t_{1/2} = ln 2 / (3.82 * 24 * 3600) = 2.10 * 10^-6 s^-1

13(a)(ii)Activity and number of atomsRadioactivity and nuclear energy / Radioactive decay1/2
Formulae and calculationTeacher review

Question paper

Radon (Rn-222) is a radioactive gas with no colour, smell or taste, released from underground bedrock or concrete containing granite. It decays by emitting α particles with a half-life of 3.82 days.

Inside buildings, the average activity due to radon in 1 m^3 of air is about 48 Bq. Estimate the average number of radon atoms in 1 m^3 of air inside buildings.

Marking reference

A = kN => N = 48 / (2.10 * 10^-6) = 2.29 * 10^7

Student response

A = k N
N = 48 / k
= 2.29 × 10⁷

Original student-response crop
Marking pointScoreOutcome
Substitution: N = 48 / (2.10 * 10^-6)0/1Not awarded
Answer: 2.29 * 10^7 (Accept: 2.28 ~ 2.3 * 10^7)1/1Awarded

Feedback and mark-loss analysis

The answer contains A = kN, N = 48/k and the correct result. The original system deducted a method mark for not rewriting the value of k; this needs review.

Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

Improvement and reference response

Check the exact demand, then complete the correction using this reference:

A = kN => N = 48 / (2.10 * 10^-6) = 2.29 * 10^7

13(a)(iii)Internal exposure to radonRadioactivity and nuclear energy / Radioactive decay2/2
Causal explanation

Question paper

Radon (Rn-222) is a radioactive gas with no colour, smell or taste, released from underground bedrock or concrete containing granite. It decays by emitting α particles with a half-life of 3.82 days.

Why is indoor radon considered harmful to human although α particles have limited penetrating power?

Marking reference

As radon is a gas that can be inhaled into the lungs of human, the relatively strong ionizing power of alpha particles emitted by decaying radon / radioactive gas might affect the organs / cells nearby.

Student response

As human inhale radon in indoor is difficult to be sense by normal feeling. As if human inhale it, α-particle has strong ionizing power. Thus harmful to body.

Original student-response crop
Marking pointScoreOutcome
Radon is a gas that can be inhaled into the lungs.1/1Awarded
Alpha particles have strong ionizing power and can damage organs/cells nearby.1/1Awarded

Feedback and mark-loss analysis

Inhalation and the strong ionising power of alpha particles are correctly linked to the risk.

Improvement and reference response

Keep this approach and use the following reference for a final check:

As radon is a gas that can be inhaled into the lungs of human, the relatively strong ionizing power of alpha particles emitted by decaying radon / radioactive gas might affect the organs / cells nearby.

13(b)Alpha and beta decay sequenceRadioactivity and nuclear energy / Radioactive decay2/2
Diagrams and graphs

Question paper

Rn-222 belongs to a decay series starting from uranium-238 (U-238). U-238 decays in the sequence α, β, β, α to form thorium-230 (Th-230).

Rn-222 belongs to a decay series starting from uranium-238 (U-238). It is known that U-238 undergoes decay in the sequence α-β-β-α to become thorium-230 (Th-230). Complete the decay series below from U-238 to Th-230 using arrows.

Original question figure

Marking reference

U-238 (Z=92, A=238) → Th-234 (90,234) → Pa-234 (91,234) → U-234 (92,234) → Th-230 (90,230). The changes are α, β⁻, β⁻, α respectively; use directed arrows on the graph.

Original marking-scheme figure · page 66

Student response

238 92 U, 234 90, 91, 92, 230 90

Original student-response crop
Marking pointScoreOutcome
All four decay arrows have the correct direction and positions: α, β⁻, β⁻, α, ending at Th-230.2/2Awarded

Feedback and mark-loss analysis

All four α, β⁻, β⁻, α decay arrows have the correct direction and positions, correctly linking U-238 to Th-230.

Improvement and reference response

Keep this approach and use the following reference for a final check:

U-238 (Z=92, A=238) → Th-234 (90,234) → Pa-234 (91,234) → U-234 (92,234) → Th-230 (90,230). The changes are α, β⁻, β⁻, α respectively; use directed arrows on the graph.

學生單次評核報告Student assessment report
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REPORT 01 · PHYSICS · PAPER 1B · 2024

學生單次評核報告Student Assessment Report

陳子朗Ethan Chan
5A
5A-17
物理科 · 卷一乙Physics · Paper 1B

評核日期:2026-08-19 | 報告日期:2026-09-29Assessment: 19 Aug 2026 | Report: 29 Sep 2026

60/84 · 得分 / Score71.4%
已評核Assessed13 大題13 questions46 小題46 subquestions
本卷取得Paper score71.4%60 / 84 分60 / 84 marks
失分Marks lost24 分24 marks按本報告分數計算Based on the report score

本卷表現Paper performance按本卷實得分計算,不代表班級百分位或 DSE 等級。Rates are based on this paper only, not class percentiles or a predicted DSE level.

本卷取得 60/84 分(71.4%)。力和運動表現較穩定;熱和氣體及電和磁是優先鞏固範疇。重點包括熱輻射、質量單位換算、電阻變化及渦流解釋。The score is 60/84 (71.4%). Force and motion is the strongest area. Prioritise heat and gases, and electricity and magnetism, particularly thermal radiation, mass conversion, resistance changes and eddy currents.

已考課題得分率Scores by assessed topic

熱和氣體Heat and gases 6/1250.0%
力和運動Force and motion 19/2286.4%
波動Waves 16/2176.2%
電和磁Electricity and magnetism 12/2157.1%
放射現象和核能Radioactivity and nuclear energy 7/887.5%

範圍:第 1–13 題,共 84 分。待覆核項目已在逐題評核標示。Scope: Questions 1–13, worth 84 marks. Items requiring review are marked in the question section.

知識地圖Knowledge map每個節點對應一個實際小題。父層以分數加總;未考內容不列出。Each node maps to one assessed subquestion. Parent totals sum the marks; unassessed content is omitted.

表現穩定 ≥80%Secure ≥80%待鞏固 60–<80%Developing 60–<80%需改善 <60%Needs attention <60%

只展示本卷已考內容;百分比反映相關小題的得分,並非對所有概念的全面測量。Only assessed content is shown. Percentages describe performance on the linked subquestions, not comprehensive mastery of each concept.

熱和氣體Heat and gases6/12 · 50.0%

溫度、熱和內能Temperature, heat and internal energy

力和運動Force and motion19/22 · 86.4%
波動Waves16/21 · 76.2%

波的本質Nature of waves

光的波動性質Wave properties of light

光的折射Refraction of light

折射角Angle of refraction · 8(b)100%表現穩定Secure · 2/2
視深計算Apparent depth · 8(c)100%表現穩定Secure · 2/2
電和磁Electricity and magnetism12/21 · 57.1%
放射現象和核能Radioactivity and nuclear energy7/8 · 87.5%

應試技巧Exam skills依小題主要作答要求分為六類;每小題只歸入一類。這是本卷題型觀察,不是另加的技巧分。Subquestions are grouped into six categories by their main demand, with each assigned once. These are paper-based observations, not additional marks.

本卷技巧得分率Performance by response demand

按實際小題分數計算25%50%75%100%審題與判斷62.5%公式與運算75.9%因果解釋65.2%圖像表達80.0%實驗設計66.7%綜合推論66.7%

外圈 100% · 綜合推論只涉及一小題Outer ring: 100% · Integrated reasoning has one subquestion

審題與判斷Reading and judgement 5/862.5%
公式與運算Formulae and calculation 22/2975.9%
因果解釋Causal explanation 15/2365.2%
圖像表達Diagrams and graphs 12/1580.0%
實驗設計Experimental design 4/666.7%
綜合推論Integrated reasoning 2/366.7%

逐題評核Question-by-question review

1(a)熱傳遞方式Heat transfer熱和氣體 / 溫度、熱和內能Heat and gases / Temperature, heat and internal energy1/1
審題與判斷Reading and judgement

題目Question paper

一瓶溫度為 4 °C 的水從雪櫃取出,放在桌上。室溫為 30 °C。A bottle of water at 4 °C is taken out of a refrigerator and placed on a table. The room temperature is 30 °C.

指出熱量由周圍環境傳至水瓶的一種方式。State one way of heat transfer from the surroundings to the bottle of water.

評卷參考Marking reference

熱傳導或輻射。conduction / radiation

學生作答Student response

Radiation from Sun to bottle

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出傳導或輻射conduction / radiation1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

已指出輻射,取得此評分點。Radiation is correctly identified as a heat-transfer mechanism.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

熱傳導或輻射。conduction / radiation

1(b)鋁箔與熱輻射Aluminium foil and thermal radiation熱和氣體 / 溫度、熱和內能Heat and gases / Temperature, heat and internal energy0/2
因果解釋Causal explanation

題目Question paper

一瓶溫度為 4 °C 的水從雪櫃取出,放在桌上。室溫為 30 °C。A bottle of water at 4 °C is taken out of a refrigerator and placed on a table. The room temperature is 30 °C.

解釋用鋁箔包裹水瓶會否加快水的升溫速率。Explain whether wrapping the bottle with an aluminum foil will speed up the rate of temperature increase.

評卷參考Marking reference

不會。鋁箔的銀色表面是輻射的不良吸收體/良好反射體。Will not, as the silvery surface of aluminum foil is a poor radiation absorber / good radiation reflector.

學生作答Student response

As Al foil is a good conductor of heat, which speed up the heat transfer from surrounding to bottle

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出不會加快升溫State 'Will not'.0/1未取得Not awarded
指出銀色表面不良吸收/良好反射輻射Silvery surface of aluminum foil is a poor radiation absorber / good radiation reflector.0/1未取得Not awarded

評語與失分分析Feedback and mark-loss analysis

以導熱性解釋鋁箔會加快升溫,忽略銀色表面對輻射的反射作用。The answer uses thermal conductivity to predict faster warming, overlooking the reflective surface and its low absorption of radiation.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

不會。鋁箔的銀色表面是輻射的不良吸收體/良好反射體。Will not, as the silvery surface of aluminum foil is a poor radiation absorber / good radiation reflector.

1(c)(i)凝結水滴的來源Source of condensed droplets熱和氣體 / 溫度、熱和內能Heat and gases / Temperature, heat and internal energy0/1
審題與判斷Reading and judgement

題目Question paper

一瓶溫度為 4 °C 的水從雪櫃取出,放在桌上。室溫為 30 °C。 一段時間後,水瓶表面形成水珠。A bottle of water at 4 °C is taken out of a refrigerator and placed on a table. The room temperature is 30 °C. After a period of time, water droplets form on the surface of the bottle.

指出瓶外水滴的來源。State the source of the water droplets.

評卷參考Marking reference

周圍空氣中的水蒸氣/水分。The water droplets come from the moisture / water vapour in the air (surroundings).

學生作答Student response

air

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出空氣中的水蒸氣/水分The water droplets come from the moisture / water vapour in the air (surroundings).0/1未取得Not awarded

評語與失分分析Feedback and mark-loss analysis

只寫「air」,未指出水蒸氣,答案欠具體。“Air” is too general: the source must be identified as water vapour or moisture in the air.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

周圍空氣中的水蒸氣/水分。The water droplets come from the moisture / water vapour in the air (surroundings).

1(c)(ii)潛熱與質量單位Latent heat and mass conversion熱和氣體 / 溫度、熱和內能Heat and gases / Temperature, heat and internal energy0/2
公式與運算Formulae and calculation

題目Question paper

一瓶溫度為 4 °C 的水從雪櫃取出,放在桌上。室溫為 30 °C。 一段時間後,水瓶表面形成水珠。A bottle of water at 4 °C is taken out of a refrigerator and placed on a table. The room temperature is 30 °C. After a period of time, water droplets form on the surface of the bottle.

瓶外收集到 0.40 g 水滴。估算凝結時釋放的潛熱。水的比汽化潛熱為 2.26 × 10⁶ J kg⁻¹。Suppose 0.40 g of water droplets are collected on the surface of the bottle. Estimate the latent heat released from these droplets. Given: specific latent heat of vaporization of water = 2.26 x 10^6 J kg^-1

評卷參考Marking reference

E = ml = (0.40 × 10⁻³)(2.26 × 10⁶) = 904 J。E = (0.40 x 10^-3)(2.26 x 10^6) = 904 J

學生作答Student response

E = (0.4)(2.26×10⁶)
= 9.04×10⁵ J

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
將 0.40 g 換成 kg 並代入潛熱公式Substitution: E = (0.40 x 10^-3)(2.26 x 10^6)0/1未取得Not awarded
得到 904 JAnswer: 904 J0/1未取得Not awarded

評語與失分分析Feedback and mark-loss analysis

把 0.40 g 當成 0.40 kg,導致答案大了 1000 倍。The mass 0.40 g is used as 0.40 kg, making the calculated energy 1000 times too large.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

E = ml = (0.40 × 10⁻³)(2.26 × 10⁶) = 904 J。E = (0.40 x 10^-3)(2.26 x 10^6) = 904 J

2(a)(i)原子的平均動能Mean kinetic energy of atoms熱和氣體 / 氣體Heat and gases / Gases2/2
公式與運算Formulae and calculation

題目Question paper

一個固定體積的密閉容器盛載單原子氣體氬,並維持在溫度 T₀。氬原子的方均根速率為 500 m s⁻¹。每個氬原子的質量為 6.63 × 10⁻²⁶ kg。A closed vessel of fixed volume contains argon, a monatomic gas, maintained at temperature T₀. The root-mean-square speed of the argon atoms is 500 m s⁻¹. The mass of an argon atom is 6.63 × 10⁻²⁶ kg.

氬原子的均方根速率為 500 m s⁻¹,質量為 6.63 × 10⁻²⁶ kg。計算原子的平均動能。Calculate the average kinetic energy of the argon atoms, Ek. Given that the mass of an argon atom is 6.63 x 10^-26 kg.

評卷參考Marking reference

Eₖ = ½mc² = ½(6.63 × 10⁻²⁶)(500)² ≈ 8.29 × 10⁻²¹ J。Ek = 1/2 * (6.63 x 10^-26) * (500)^2 = 8.2875 x 10^-21 J ≈ 8.29 x 10^-21 J

學生作答Student response

E_k = 1/2 (6.63×10⁻²⁶)(500)²
= 8.29×10⁻²¹ J

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
代入平均動能公式Substitution: 1/2 * (6.63 x 10^-26) * (500)^21/1已取得Awarded
得到約 8.29 × 10⁻²¹ JAnswer: 8.29 x 10^-21 J (Accept: 8.29 ~ 8.30 x 10^-21 J)1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

平均動能公式、代入及答案正確。The formula, substitution and numerical kinetic energy are correct.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

Eₖ = ½mc² = ½(6.63 × 10⁻²⁶)(500)² ≈ 8.29 × 10⁻²¹ J。Ek = 1/2 * (6.63 x 10^-26) * (500)^2 = 8.2875 x 10^-21 J ≈ 8.29 x 10^-21 J

2(a)(ii)動能與絕對溫度Kinetic energy and temperature熱和氣體 / 氣體Heat and gases / Gases1/2
公式與運算Formulae and calculation

題目Question paper

一個固定體積的密閉容器盛載單原子氣體氬,並維持在溫度 T₀。氬原子的方均根速率為 500 m s⁻¹。每個氬原子的質量為 6.63 × 10⁻²⁶ kg。A closed vessel of fixed volume contains argon, a monatomic gas, maintained at temperature T₀. The root-mean-square speed of the argon atoms is 500 m s⁻¹. The mass of an argon atom is 6.63 × 10⁻²⁶ kg.

由此或以其他方法求氣體的溫度 T₀(K)。Hence, or otherwise, find T0 (in K).

評卷參考Marking reference

Eₖ = 3RT₀/(2Nₐ),故 T₀ = 2NₐEₖ/(3R) ≈ 400 K。Ek = 3RT0 / 2NA; T0 = (2/3) * (8.29 x 10^-21 / 8.31) * (6.02 x 10^23) = 400.247 (K) ≈ 400 (K)

學生作答Student response

nRT = 1/3 N m c̄²
3/2 R T / N_A = 1/2 m c̄² = E_k
T = 3.65×10⁻¹⁸ K

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
運用平均動能與溫度關係Substitution into kinetic theory formula using Ek from (a)(i).1/1已取得Awarded
得到約 400 KAnswer: 400 (K)0/1未取得Not awarded

評語與失分分析Feedback and mark-loss analysis

列出了動能與溫度的正確關係,但最終數值不合理;保留關係式分。The relationship between kinetic energy and temperature is correct, but the final temperature is implausible. The relationship mark is retained.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

Eₖ = 3RT₀/(2Nₐ),故 T₀ = 2NₐEₖ/(3R) ≈ 400 K。Ek = 3RT0 / 2NA; T0 = (2/3) * (8.29 x 10^-21 / 8.31) * (6.02 x 10^23) = 400.247 (K) ≈ 400 (K)

2(b)定溫下的均方根速率RMS speed at constant temperature熱和氣體 / 氣體Heat and gases / Gases2/2
因果解釋Causal explanation

題目Question paper

一個固定體積的密閉容器盛載單原子氣體氬,並維持在溫度 T₀。氬原子的方均根速率為 500 m s⁻¹。每個氬原子的質量為 6.63 × 10⁻²⁶ kg。A closed vessel of fixed volume contains argon, a monatomic gas, maintained at temperature T₀. The root-mean-square speed of the argon atoms is 500 m s⁻¹. The mass of an argon atom is 6.63 × 10⁻²⁶ kg.

若容器漏出部分氬氣,而溫度維持 T₀,指出並解釋餘下氬原子均方根速率的變化。If some of the argon has been leaked from the vessel while the temperature remains at T0, state and explain the change, if any, in the root-mean-square speed of the argon atoms inside the vessel.

評卷參考Marking reference

溫度不變,原子的平均動能不變,所以均方根速率不變。As temperature remains at T0, Ek remains unchanged / cr.m.s. depends on temperature, so root-mean-square speed cr.m.s. remains unchanged.

學生作答Student response

As temperature unchange,
average kinetic energy of argon unchange.
Thus, c_rms also unchange.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出溫度不變State that Ek remains unchanged or cr.m.s. depends on temperature.1/1已取得Awarded
推論平均動能及均方根速率不變Conclude that root-mean-square speed cr.m.s. remains unchanged.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

已連結溫度不變、平均動能不變及均方根速率不變。The explanation correctly links constant temperature to constant mean kinetic energy and unchanged RMS speed.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

溫度不變,原子的平均動能不變,所以均方根速率不變。As temperature remains at T0, Ek remains unchanged / cr.m.s. depends on temperature, so root-mean-square speed cr.m.s. remains unchanged.

3(a)功與動能Work and kinetic energy力和運動 / 力與運動Force and motion / Force and motion2/2
公式與運算Formulae and calculation

題目Question paper

質量為 0.20 kg 的小木塊 P 靜止於水平桌面的 A 端。A 至 B 的桌面光滑,B 至 C 的桌面粗糙。圖 3.1 所示的水平力為 0.30 N,A 至 B 的距離為 0.75 m。忽略空氣阻力。A small block P of mass 0.20 kg rests at side A of a horizontal table. The table is smooth from A to B and rough from B to C. A horizontal force of 0.30 N acts as shown in Figure 3.1; AB = 0.75 m. Neglect air resistance.

質量 0.20 kg 的滑塊由靜止受水平力 0.30 N 作用,在光滑表面移動 0.75 m 至 B。求其速率。Find the speed of the block after it travels 0.75 m to point B.

原題插圖Original question figure

評卷參考Marking reference

Fs = ½mv²;0.30 × 0.75 = ½(0.20)v²;v = 1.5 m s⁻¹。By Fs = 1/2mv^2, 0.30 x 0.75 = 1/2 (0.20) v^2 v = 1.5 m s^-1 (Alternative: v^2 = u^2 + 2as and F = ma)

學生作答Student response

WD = F · s
1/2 (0.2) v² = (0.3)(0.75)
v = 1.5 m s⁻¹

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
代入功—動能關係或等效運動公式Substitution of values into work-energy equation (Fs = 1/2mv^2) or equivalent kinematic/force equations (v^2 = u^2 + 2as and F = ma).1/1已取得Awarded
得到 1.5 m s⁻¹Final answer v = 1.5 m s^-1 (with correct unit).1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

正確運用功與動能的關係,得到 1.5 m s⁻¹。The work–energy relationship gives the correct speed of 1.5 m s⁻¹.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

Fs = ½mv²;0.30 × 0.75 = ½(0.20)v²;v = 1.5 m s⁻¹。By Fs = 1/2mv^2, 0.30 x 0.75 = 1/2 (0.20) v^2 v = 1.5 m s^-1 (Alternative: v^2 = u^2 + 2as and F = ma)

3(b)自由體圖Free-body diagram力和運動 / 力與運動Force and motion / Force and motion2/2
圖像表達Diagrams and graphs待教師校對Teacher review

題目Question paper

質量為 0.20 kg 的小木塊 P 靜止於水平桌面的 A 端。A 至 B 的桌面光滑,B 至 C 的桌面粗糙。圖 3.1 所示的水平力為 0.30 N,A 至 B 的距離為 0.75 m。忽略空氣阻力。A small block P of mass 0.20 kg rests at side A of a horizontal table. The table is smooth from A to B and rough from B to C. A horizontal force of 0.30 N acts as shown in Figure 3.1; AB = 0.75 m. Neglect air resistance.

滑塊到達 B 時撤去水平外力。它繼續在粗糙表面由 B 移至 C,在自由體圖畫出及標示所有作用力。The horizontal force is removed when block P just reaches B. When the block continues to travel from B to C, on the free-body diagram below indicate and name the force(s) acting on the block.

原題插圖Original question figure
原題插圖Original question figure

評卷參考Marking reference

三個力:向上支持力、向下重力、向左摩擦力。A free-body diagram of block P showing three forces: 1. Normal reaction (upward) 2. Weight (downward) 3. Friction (leftward, opposing motion)

評卷參考原圖 · 第 59 頁Original marking-scheme figure · page 59

學生作答Student response

本小題以圖像作答,請對照下方原稿。This response is graphical; refer to the original crop below.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
支持力及重力的方向與標示Draw and label the vertical forces: an upward arrow (normal reaction/force) and a downward arrow (weight/gravity).1/1已取得Awarded
摩擦力的方向與標示Draw and label the horizontal force: a leftward arrow (friction) acting on block P.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

原稿畫出支持力、重力及摩擦力;方向和名稱均取得分數。The original drawing identifies normal reaction, weight and friction in the required directions.

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

三個力:向上支持力、向下重力、向左摩擦力。A free-body diagram of block P showing three forces: 1. Normal reaction (upward) 2. Weight (downward) 3. Friction (leftward, opposing motion)

3(c)平拋的鉛直位移Vertical displacement in projectile motion力和運動 / 力與運動Force and motion / Force and motion2/2
公式與運算Formulae and calculation

題目Question paper

質量為 0.20 kg 的小木塊 P 靜止於水平桌面的 A 端。A 至 B 的桌面光滑,B 至 C 的桌面粗糙。圖 3.1 所示的水平力為 0.30 N,A 至 B 的距離為 0.75 m。忽略空氣阻力。A small block P of mass 0.20 kg rests at side A of a horizontal table. The table is smooth from A to B and rough from B to C. A horizontal force of 0.30 N acts as shown in Figure 3.1; AB = 0.75 m. Neglect air resistance.

滑塊由桌邊 C 飛出後,經 0.35 s 抵達地面 K。估算桌子的高度。The block leaves side C of the table and takes 0.35 s to reach point K on the ground. Estimate the height of the table.

原題插圖Original question figure

評卷參考Marking reference

h = ½gt² = ½(9.81)(0.35)² ≈ 0.601 m。Height = 1/2 gt^2 = 1/2 (9.81)(0.35)^2 = 0.6008625 m ≈ 0.601 m Accept: 0.60 m ~ 0.613 m

學生作答Student response

s_y = u_y t + 1/2 a_y t²
= 0 + 1/2 (9.81)(0.35)²
∴ height = 0.601 m

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
代入 h = ½gt²Substitution into vertical displacement formula h = 1/2 gt^2 using g ≈ 9.81 and t = 0.35.1/1已取得Awarded
得到約 0.601 mFinal answer for height within the range 0.60 m to 0.613 m.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

以鉛直初速為零處理下墜,列式及高度正確。The vertical motion is correctly treated as starting with zero vertical speed, giving the correct height.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

h = ½gt² = ½(9.81)(0.35)² ≈ 0.601 m。Height = 1/2 gt^2 = 1/2 (9.81)(0.35)^2 = 0.6008625 m ≈ 0.601 m Accept: 0.60 m ~ 0.613 m

4(a)(i)向心力計算Centripetal force力和運動 / 圓周運動Force and motion / Circular motion2/2
公式與運算Formulae and calculation

題目Question paper

半徑為 0.50 m 的球體繞鉛直軸 ACB 以恆定角速率 6 rad s⁻¹ 旋轉,C 為球心。質量為 0.020 kg 的小塊塑膠泥 P 黏在球面上,在通過 C 的水平平面內旋轉。A sphere of radius 0.50 m rotates about a vertical axis ACB at a constant angular speed of 6 rad s⁻¹, with C at its centre. A small piece of plasticine P of mass 0.020 kg is stuck to the surface and rotates in a horizontal plane through C.

質量 0.020 kg 的膠泥 P 以角速度 6 rad s⁻¹、半徑 0.50 m 作圓周運動。求向心力。Find the magnitude of the centripetal force acting on P.

原題插圖Original question figure

評卷參考Marking reference

F = mω²r = (0.020)(6²)(0.50) = 0.36 N。F = mω^2r = 0.020 x 6^2 x 0.50 = 0.36 N

學生作答Student response

F_c = m ω² r
= (0.02)(6)²(0.5)
= 0.36 N

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
代入 F = mω²rSubstitution into centripetal force formula F = mω^2r.1/1已取得Awarded
得到 0.36 NFinal answer F = 0.36 N.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

向心力公式、質量單位及數值均正確。The centripetal-force formula, mass conversion and numerical result are correct.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

F = mω²r = (0.020)(6²)(0.50) = 0.36 N。F = mω^2r = 0.020 x 6^2 x 0.50 = 0.36 N

4(a)(ii)離開圓周時的切線方向Tangential velocity on release力和運動 / 圓周運動Force and motion / Circular motion1/1
圖像表達Diagrams and graphs待教師校對Teacher review

題目Question paper

半徑為 0.50 m 的球體繞鉛直軸 ACB 以恆定角速率 6 rad s⁻¹ 旋轉,C 為球心。質量為 0.020 kg 的小塊塑膠泥 P 黏在球面上,在通過 C 的水平平面內旋轉。A sphere of radius 0.50 m rotates about a vertical axis ACB at a constant angular speed of 6 rad s⁻¹, with C at its centre. A small piece of plasticine P of mass 0.020 kg is stuck to the surface and rotates in a horizontal plane through C.

球體加速旋轉,P 最終在圖示位置離開球面。在俯視圖上指出 P 剛離開時的運動方向。The sphere's angular speed is increasing. If P finally leaves the sphere at the position shown in Figure 4.1(b) (Top view from A). Indicate on Figure 4.1(b) the direction of motion of P when it just leaves the sphere.

原題插圖Original question figure

評卷參考Marking reference

由 P 點沿圓周切線、按原來旋轉方向畫箭頭;圖示為左下方。速度不指向圓心。Draw an arrow from P tangent to the circular path, in the direction of motion (down-left in Figure 4.1(b)). The velocity is not directed towards the centre.

評卷參考原圖 · 第 59 頁Original marking-scheme figure · page 59

學生作答Student response

本小題以圖像作答,請對照下方原稿。This response is graphical; refer to the original crop below.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
沿 P 點切線畫出離開方向Draw an arrow tangential to the circular path at P, in the direction of release.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

離開圓周一刻的速度沿切線;原稿箭頭符合此方向。The velocity on release is tangential. The arrow on the original script follows the tangent.

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

由 P 點沿圓周切線、按原來旋轉方向畫箭頭;圖示為左下方。速度不指向圓心。Draw an arrow from P tangent to the circular path, in the direction of motion (down-left in Figure 4.1(b)). The velocity is not directed towards the centre.

4(b)(i)角速度比較Comparing angular speeds力和運動 / 圓周運動Force and motion / Circular motion1/1
審題與判斷Reading and judgement

題目Question paper

半徑為 0.50 m 的球體繞鉛直軸 ACB 以恆定角速率 6 rad s⁻¹ 旋轉,C 為球心。質量為 0.020 kg 的小塊塑膠泥 P 黏在球面上,在通過 C 的水平平面內旋轉。 另一小塊塑膠泥 Q 黏在球面上,如圖 4.2 所示。A sphere of radius 0.50 m rotates about a vertical axis ACB at a constant angular speed of 6 rad s⁻¹, with C at its centre. A small piece of plasticine P of mass 0.020 kg is stuck to the surface and rotates in a horizontal plane through C. Another piece of plasticine Q is stuck to the sphere’s surface as shown in Figure 4.2.

指出同一旋轉球體上的 P 和 Q 是否具有相同角速度。State whether P and Q have the same angular speed.

原題插圖Original question figure

評卷參考Marking reference

角速度相同。same angular speed

學生作答Student response

Yes

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出相同角速度State that the angular speed is the same.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

同一剛體上的兩點角速度相同,判斷正確。The two points on the same rigid body have the same angular speed.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

角速度相同。same angular speed

4(b)(ii)向心加速度與半徑Centripetal acceleration and radius力和運動 / 圓周運動Force and motion / Circular motion2/2
因果解釋Causal explanation

題目Question paper

半徑為 0.50 m 的球體繞鉛直軸 ACB 以恆定角速率 6 rad s⁻¹ 旋轉,C 為球心。質量為 0.020 kg 的小塊塑膠泥 P 黏在球面上,在通過 C 的水平平面內旋轉。 另一小塊塑膠泥 Q 黏在球面上,如圖 4.2 所示。A sphere of radius 0.50 m rotates about a vertical axis ACB at a constant angular speed of 6 rad s⁻¹, with C at its centre. A small piece of plasticine P of mass 0.020 kg is stuck to the surface and rotates in a horizontal plane through C. Another piece of plasticine Q is stuck to the sphere’s surface as shown in Figure 4.2.

解釋 P 和 Q 的向心加速度大小是否相同。Explain whether P and Q have the same magnitude of centripetal acceleration.

原題插圖Original question figure

評卷參考Marking reference

a = ω²r;兩者 ω 相同,而 Q 的旋轉半徑較小,所以 aQ < aP。different / smaller magnitude of centripetal acceleration (aQ < aP) as Q takes a different / smaller radius (rQ < rP)

學生作答Student response

NO. As r_Q < r_P
a_Q < a_P

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出 Q 的向心加速度較小State that the magnitude of centripetal acceleration is different or smaller (aQ < aP).1/1已取得Awarded
以 Q 的半徑較小解釋Explain that Q has a smaller radius of rotation (rQ < rP).1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

正確指出半徑較小的 Q 向心加速度較小。The answer correctly identifies the smaller centripetal acceleration at the smaller radius of Q.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

a = ω²r;兩者 ω 相同,而 Q 的旋轉半徑較小,所以 aQ < aP。different / smaller magnitude of centripetal acceleration (aQ < aP) as Q takes a different / smaller radius (rQ < rP)

5(a)縱波的位移圖Displacement graph of a sound wave波動 / 波的本質Waves / Nature of waves0/2
圖像表達Diagrams and graphs待教師校對Teacher review

題目Question paper

圖 5.1 顯示揚聲器產生的聲波在某一瞬間的空氣粒子分布。聲波向右傳播,P、Q、R、S、T 為圖中標示的區域。Figure 5.1 shows the distribution of air particles at an instant in a sound wave produced by a loudspeaker. The wave travels to the right; P, Q, R, S and T are the marked regions.

根據空氣粒子的瞬時分佈,在網格上畫出位移—距離圖。向右的位移取正值。Sketch the displacement-distance graph of the air particles at that instant in the grid provided. Take the displacement to the right as positive (+).

原題插圖Original question figure
原題插圖Original question figure

評卷參考Marking reference

P、R、T 為零位移;Q、S 的位移為相反極值。由 P 起先向下至 Q 的波谷,再經 R 回到零位移,至 S 的波峰。Displacement is zero at the centres of compression and rarefaction (P, R, T), with opposite displacement extrema at Q and S. Starting at P, the curve first moves below the axis, reaches its first trough at Q, crosses zero at R, and reaches a crest at S.

評卷參考原圖 · 第 60 頁Original marking-scheme figure · page 60

學生作答Student response

本小題以圖像作答,請對照下方原稿。This response is graphical; refer to the original crop below.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
曲線起點及首段方向正確Correct zero-displacement starting position and initial direction.0/1未取得Not awarded
波長、零位移及極值位置正確Correct phase, wavelength and positions of zero displacement and extrema.0/1未取得Not awarded

評語與失分分析Feedback and mark-loss analysis

位移曲線起點及相位與粒子分佈不符。不能把粒子密度直接當作位移。The starting displacement and phase do not match the particle distribution. Particle density must not be copied directly as displacement.

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

P、R、T 為零位移;Q、S 的位移為相反極值。由 P 起先向下至 Q 的波谷,再經 R 回到零位移,至 S 的波峰。Displacement is zero at the centres of compression and rarefaction (P, R, T), with opposite displacement extrema at Q and S. Starting at P, the curve first moves below the axis, reaches its first trough at Q, crosses zero at R, and reaches a crest at S.

5(b)(i)粒子的最高速率Maximum particle speed波動 / 波的本質Waves / Nature of waves0/1
審題與判斷Reading and judgement待教師校對Teacher review

題目Question paper

圖 5.1 顯示揚聲器產生的聲波在某一瞬間的空氣粒子分布。聲波向右傳播,P、Q、R、S、T 為圖中標示的區域。Figure 5.1 shows the distribution of air particles at an instant in a sound wave produced by a loudspeaker. The wave travels to the right; P, Q, R, S and T are the marked regions.

在 P、Q、R、S、T 中指出一個粒子運動速率最大的區域。At the instant shown, state a region (P, Q, R, S or T) in which the air particles are moving with the highest speed.

原題插圖Original question figure

評卷參考Marking reference

P、R、T 中任一個區域。P / R / T

學生作答Student response

P , R , T

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出 P、R、T 中其中一個區域Identify any one of the points P, R, or T (the peaks or troughs).0/1未取得Not awarded

評語與失分分析Feedback and mark-loss analysis

原答列出 P、R、T,均在參考答案之列。原判因多選而給 0/1;此項保留給教師校對。The answer lists P, R and T, all of which appear in the reference. The original system awarded 0/1 for listing multiple regions; this decision is retained for teacher review.

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

P、R、T 中任一個區域。P / R / T

5(b)(ii)最低氣壓區域Region of minimum pressure波動 / 波的本質Waves / Nature of waves1/1
審題與判斷Reading and judgement

題目Question paper

圖 5.1 顯示揚聲器產生的聲波在某一瞬間的空氣粒子分布。聲波向右傳播,P、Q、R、S、T 為圖中標示的區域。Figure 5.1 shows the distribution of air particles at an instant in a sound wave produced by a loudspeaker. The wave travels to the right; P, Q, R, S and T are the marked regions.

指出圖示瞬間氣壓最低的區域。At the instant shown, state a region (P, Q, R, S or T) in which the air pressure is the lowest.

原題插圖Original question figure

評卷參考Marking reference

R;疏落中心的氣壓最低。R: the rarefaction region has the lowest air pressure.

學生作答Student response

R

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出 RIdentify R as the region of minimum air pressure.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

選出 R,符合最低氣壓的疏落中心。R is correctly selected as the rarefaction region with minimum pressure.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

R;疏落中心的氣壓最低。R: the rarefaction region has the lowest air pressure.

6(a)光柵間距Diffraction-grating spacing波動 / 光的波動性質Waves / Wave properties of light3/3
公式與運算Formulae and calculation

題目Question paper

除去光碟(CD)的保護層及反射層後,光碟成為具有等距平行狹縫的衍射光柵[圖 6.1(a)]。圖 6.1(b) 的雷射裝置用來量度狹縫間距 d。光柵與屏幕相距 L = 0.10 m;兩個一級亮紋相距 x = 0.092 m;紅色雷射光的波長 λ = 650 nm。After removing a CD’s protective coating and reflective layer, the CD becomes a diffraction grating with evenly spaced parallel slits [Figure 6.1(a)]. The laser set-up in Figure 6.1(b) measures the slit separation d. The grating–screen separation is L = 0.10 m, the separation between the first-order maxima is x = 0.092 m, and the red laser wavelength is λ = 650 nm.

利用原圖所示的激光波長、屏幕距離及亮點間距,估算光柵間距 d。Estimate d.

原題插圖Original question figure

評卷參考Marking reference

tan θ = (0.092/2)/0.10;d sin θ = λ;d ≈ 1.56 × 10⁻⁶ m。Apply d sin θ = mλ. tan θ = (x/2) / L => θ = 24.702430° or sin θ = (x/2) / sqrt(L^2 + (x/2)^2) = 0.417906. d = λ / sin θ = (650 x 10^-9) / 0.418 = 1.555375 x 10^-6 m ≈ 1.56 μm.

學生作答Student response

d sin θ = n λ
d sin ( tan⁻¹ ( 0.092/2 / 0.1 ) ) = (1)(650 × 10⁻⁹)
d = 1.56 × 10⁻⁶ m

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
正確計算衍射角Correct substitution or calculation to find the angle θ (e.g., using tan θ = (x/2)/L or sin θ calculation).1/1已取得Awarded
代入光柵方程Correct substitution into the diffraction grating formula d sin θ = mλ (where m=1).1/1已取得Awarded
得到約 1.56 μmFinal answer for d ≈ 1.56 μm (Accept: 1.56 μm ~ 1.6 μm).1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

以正切關係求角度,再代入光柵方程,計算完整。The diffraction angle is obtained from the tangent relation and used correctly in the grating equation.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

tan θ = (0.092/2)/0.10;d sin θ = λ;d ≈ 1.56 × 10⁻⁶ m。Apply d sin θ = mλ. tan θ = (x/2) / L => θ = 24.702430° or sin θ = (x/2) / sqrt(L^2 + (x/2)^2) = 0.417906. d = λ / sin θ = (650 x 10^-9) / 0.418 = 1.555375 x 10^-6 m ≈ 1.56 μm.

6(b)波長與條紋間距Wavelength and fringe separation波動 / 光的波動性質Waves / Wave properties of light2/2
因果解釋Causal explanation

題目Question paper

除去光碟(CD)的保護層及反射層後,光碟成為具有等距平行狹縫的衍射光柵[圖 6.1(a)]。圖 6.1(b) 的雷射裝置用來量度狹縫間距 d。光柵與屏幕相距 L = 0.10 m;兩個一級亮紋相距 x = 0.092 m;紅色雷射光的波長 λ = 650 nm。After removing a CD’s protective coating and reflective layer, the CD becomes a diffraction grating with evenly spaced parallel slits [Figure 6.1(a)]. The laser set-up in Figure 6.1(b) measures the slit separation d. The grating–screen separation is L = 0.10 m, the separation between the first-order maxima is x = 0.092 m, and the red laser wavelength is λ = 650 nm.

若改用綠色激光,指出並解釋亮點間距 x 的變化。State and explain the change in x if green laser light is used.

原題插圖Original question figure

評卷參考Marking reference

x 減少。綠光波長較短,故衍射角較小,亮點間距亦較小。x will decrease as λ decreases, sin θ and θ will decrease.

學生作答Student response

Decrease .
As green laser has shorter wavelength, sin θ reduce
θ reduce . Thus x reduce .

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出 x 減少State that x will decrease.1/1已取得Awarded
以波長及衍射角減少解釋Explain that as λ decreases, sin θ (and thus θ) will decrease according to the diffraction formula.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

清楚連結波長減少、衍射角減少及間距減少。The explanation correctly links shorter wavelength to a smaller diffraction angle and reduced separation.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

x 減少。綠光波長較短,故衍射角較小,亮點間距亦較小。x will decrease as λ decreases, sin θ and θ will decrease.

7(a)氣溫與聲速Air temperature and sound speed波動 / 聲音Waves / Sound1/1
審題與判斷Reading and judgement

題目Question paper

圖 7.1 顯示聲速隨空氣溫度的變化。Figure 7.1 shows the speed of sound at different air temperatures.

參照圖線,指出聲速與空氣溫度的關係。With reference to the graph, state the relationship between the speed of sound and the air temperature.

原題插圖Original question figure

評卷參考Marking reference

空氣溫度愈高,聲速愈大;圖示近似線性增加。The speed of sound increases (linearly) with air temperature. / The higher the air temperature, the greater is the speed of sound.

學生作答Student response

Speed of sound increase when air temperature increase.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出氣溫上升時聲速增加State that the speed of sound increases with air temperature.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

正確讀出溫度上升時聲速增加。The graph is correctly read as showing increased sound speed at higher temperature.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

空氣溫度愈高,聲速愈大;圖示近似線性增加。The speed of sound increases (linearly) with air temperature. / The higher the air temperature, the greater is the speed of sound.

7(b)聲波在空氣層的折射Refraction through air layers波動 / 聲音Waves / Sound2/2
因果解釋Causal explanation

題目Question paper

夜間地面冷卻。圖 7.2 顯示聲音從遠處鐘樓傳至觀察者的路徑。At night the ground cools. Figure 7.2 shows sound travelling from a distant tower clock to an observer.

利用不同高度空氣層的溫度差,解釋圖 7.2 中聲波向地面彎曲的情況。How does the temperature difference between air layers above the ground explain the situation in Figure 7.2?

原題插圖Original question figure

評卷參考Marking reference

近地面空氣較冷、聲速較低;聲波由上方較暖空氣傳入下方較冷空氣時向法線偏折,故路徑向地面彎曲。The air near the ground is cooler while the air layers higher above are relatively warmer, the sound wave bends downward (towards the normal) as it travels slower when going from a higher temperature (upper) layer into a low temperature (lower) layer and vice versa, i.e. refraction occurs.

學生作答Student response

Temperature decrease from sky to ground uniformly.
As sound travel from fast region to slow region, it bends toward to normal of air layers.
Thus, sound moves toward ground.

學生原稿裁圖Original student-response crop
學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出近地面較冷/上方較暖Identify that air near the ground is cooler than air layers higher above.1/1已取得Awarded
以聲速差異及折射方向解釋Explain that sound bends downward (refraction) because it travels slower in the cooler lower layer.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

已交代上暖下冷、聲速差異及聲波向下折射。The answer identifies warmer air above cooler air and explains the downward refraction of sound.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

近地面空氣較冷、聲速較低;聲波由上方較暖空氣傳入下方較冷空氣時向法線偏折,故路徑向地面彎曲。The air near the ground is cooler while the air layers higher above are relatively warmer, the sound wave bends downward (towards the normal) as it travels slower when going from a higher temperature (upper) layer into a low temperature (lower) layer and vice versa, i.e. refraction occurs.

7(c)(i)光速與聲速的比值Ratio of light speed to sound speed波動 / 聲音Waves / Sound0/1
公式與運算Formulae and calculation

題目Question paper

圖 7.1 顯示聲速隨空氣溫度的變化。 已知空氣溫度為 10 °C。參考圖 7.1。Figure 7.1 shows the speed of sound at different air temperatures. The air temperature is 10 °C. Refer to Figure 7.1.

估算光速與聲速的比值。Estimate the ratio of speed of light to the speed of sound; c/v.

原題插圖Original question figure

評卷參考Marking reference

(3.00 × 10⁸)/337 ≈ 8.90 × 10⁵。Speed ratio = (3.00 x 10^8) / 337 = 8.90208 x 10^5 ≈ 8.90 x 10^5

學生作答Student response

[Crossed out: c / v]

c / v = (3 × 10⁸) / 337
= 8.90 × 10⁶

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
得到約 8.90 × 10⁵Correct calculation of the ratio of speed of light to speed of sound (approx 8.90 x 10^5).0/1未取得Not awarded

評語與失分分析Feedback and mark-loss analysis

算式正確,但答案的十進位次方錯了一位。The division is set up correctly, but the exponent in the final answer is one power of ten too large.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

(3.00 × 10⁸)/337 ≈ 8.90 × 10⁵。Speed ratio = (3.00 x 10^8) / 337 = 8.90208 x 10^5 ≈ 8.90 x 10^5

7(c)(ii)雷暴距離Distance to a thunderstorm波動 / 聲音Waves / Sound1/2
公式與運算Formulae and calculation待教師校對Teacher review

題目Question paper

圖 7.1 顯示聲速隨空氣溫度的變化。 已知空氣溫度為 10 °C。參考圖 7.1。Figure 7.1 shows the speed of sound at different air temperatures. The air temperature is 10 °C. Refer to Figure 7.1.

觀察者在看見閃電 3.0 s 後聽到雷聲,估算雷暴距離。Estimate the distance of a thunderstorm from an observer O if thunder is heard 3.0 s after lightning is seen by O.

原題插圖Original question figure

評卷參考Marking reference

d ≈ 337 × 3.0 = 1011 m;約 1.01 km。Distance = 337 x 3.0 = 1011 m. Accept: 1010 m ~ 1011 m. e.c.f. from (c)(i) using incorrect sound speed.

學生作答Student response

⇒ [Crossed out: d = c · t]
[Crossed out: d = v · (t + 3)]

[Crossed out: 1 = c/v · t / (t + 3)]

[Crossed out: v/c t + v/c · 3 = t]

t = 3.37 × 10⁻⁶ s

∴ d = c · t = 1010 m

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
列出距離計算的代入步驟Substitution: Multiply sound speed by time (337 x 3.0).0/1未取得Not awarded
得到約 1010–1011 mFinal answer: 1011 m (Accept 1010 m ~ 1011 m).1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

以光的傳播時間求得 1010 m;原判只給結果分。替代解法的步驟分須連同刪改痕跡校對。The alternative calculation uses light-travel time and gives 1010 m. The original system awarded only the answer mark; the method mark needs review against the crossed-out working.

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

d ≈ 337 × 3.0 = 1011 m;約 1.01 km。Distance = 337 x 3.0 = 1011 m. Accept: 1010 m ~ 1011 m. e.c.f. from (c)(i) using incorrect sound speed.

8(a)折射光線與虛像Refraction and a virtual image波動 / 光的折射Waves / Refraction of light2/2
圖像表達Diagrams and graphs待教師校對Teacher review

題目Question paper

圖 8.1 顯示一支放在水杯中的鉛筆,觀察者鉛直向下觀看。水的折射率為 1.33。光線 P 和 Q 由鉛筆尖 O 發出,Q 沿鉛直方向。圖並非按比例繪畫。Figure 8.1 shows a pencil in a glass of water viewed vertically downwards by an observer. The refractive index of water is 1.33. Rays P and Q come from the pencil tip O, with Q along the vertical. The diagram is not drawn to scale.

在圖 8.1 完成光線路徑,並以 I 標示觀察者所見的 O 的像。On Figure 8.1, complete the paths of these light rays and indicate the image of O seen by the observer (label this as I).

原題插圖Original question figure

評卷參考Marking reference

光線由水進入空氣時偏離法線。將折射光線反向延長,交於 O 上方的虛像 I。MS diagram shows two rays originating from point O at the bottom of the pencil in water. Upon reaching the water-air interface, they refract away from the normal. The refracted rays are traced back (dashed lines) to intersect at point I, which is higher than O. A vertical dashed line connects O and I. The distance from the water surface to O is labeled 0.10 m.

評卷參考原圖 · 第 61 頁Original marking-scheme figure · page 61

學生作答Student response

本小題以圖像作答,請對照下方原稿。This response is graphical; refer to the original crop below.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
完成折射光線及方向Draw two rays from O refracting away from the normal at the water surface.1/1已取得Awarded
反向延長光線並標示虛像 ICorrect location of image I formed by the intersection of the two back-projected refracted rays.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

原圖已畫出折射光線及虛像;原系統標記圖像清晰度需覆核。The refracted rays and virtual image are present. The original system flagged image legibility for checking.

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

光線由水進入空氣時偏離法線。將折射光線反向延長,交於 O 上方的虛像 I。MS diagram shows two rays originating from point O at the bottom of the pencil in water. Upon reaching the water-air interface, they refract away from the normal. The refracted rays are traced back (dashed lines) to intersect at point I, which is higher than O. A vertical dashed line connects O and I. The distance from the water surface to O is labeled 0.10 m.

8(b)折射角Angle of refraction波動 / 光的折射Waves / Refraction of light2/2
公式與運算Formulae and calculation

題目Question paper

圖 8.1 顯示一支放在水杯中的鉛筆,觀察者鉛直向下觀看。水的折射率為 1.33。光線 P 和 Q 由鉛筆尖 O 發出,Q 沿鉛直方向。圖並非按比例繪畫。Figure 8.1 shows a pencil in a glass of water viewed vertically downwards by an observer. The refractive index of water is 1.33. Rays P and Q come from the pencil tip O, with Q along the vertical. The diagram is not drawn to scale.

光線 P 和 Q 的夾角為 1.5°,求 P 的折射角。The angle between ray P and ray Q is 1.5°. Find the angle of refraction of ray P.

原題插圖Original question figure

評卷參考Marking reference

sin r = 1.33 sin 1.5°;r ≈ 2.00°。1.33 = sin r / sin 1.5°; r = 1.995175° ≈ 2.00°

學生作答Student response

1 sin θ = 1.33 sin 1.5°
θ = 2.00°

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
代入斯涅爾定律Substitution into Snell's Law: 1.33 = sin r / sin 1.5°.1/1已取得Awarded
得到約 2.00°Final answer: r ≈ 2.00°.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

斯涅爾定律的代入及折射角正確。Snell’s law is correctly applied to obtain the angle of refraction.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

sin r = 1.33 sin 1.5°;r ≈ 2.00°。1.33 = sin r / sin 1.5°; r = 1.995175° ≈ 2.00°

8(c)視深計算Apparent depth波動 / 光的折射Waves / Refraction of light2/2
公式與運算Formulae and calculation

題目Question paper

圖 8.1 顯示一支放在水杯中的鉛筆,觀察者鉛直向下觀看。水的折射率為 1.33。光線 P 和 Q 由鉛筆尖 O 發出,Q 沿鉛直方向。圖並非按比例繪畫。Figure 8.1 shows a pencil in a glass of water viewed vertically downwards by an observer. The refractive index of water is 1.33. Rays P and Q come from the pencil tip O, with Q along the vertical. The diagram is not drawn to scale.

水深為 0.10 m,求像 I 與水面的距離。Hence, or otherwise, find the distance between image I and the water surface if the depth of water is 0.10 m.

原題插圖Original question figure

評卷參考Marking reference

h′ = 0.10 tan 1.5° / tan 2.00° ≈ 0.0752 m。h1 / h = tan 1.5° / tan 2.00° = 0.751681 (or tan 1.5° = PQ/0.10 & tan 2° = PQ/h1); h1 ≈ 0.075 m (i.e. 7.5 cm). Accept: real depth / apparent depth = n.

學生作答Student response

⇒ PQ = 0.1 tan 1.5°
[Crossed out: tan(2.00°) = PQ / d_req.]

d_req. = (0.1 tan 1.5°) / tan(2.00°)
d = 0.0752 m

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
建立視深與三角比關係Method: Use of tan ratios or the apparent depth formula (h/h' = n) with explicit steps shown.1/1已取得Awarded
得到約 0.075 mFinal answer: h1 ≈ 0.075 m or 7.5 cm.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

以三角比求出正確的視深。The trigonometric relationship gives the correct apparent depth.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

h′ = 0.10 tan 1.5° / tan 2.00° ≈ 0.0752 m。h1 / h = tan 1.5° / tan 2.00° = 0.751681 (or tan 1.5° = PQ/0.10 & tan 2° = PQ/h1); h1 ≈ 0.075 m (i.e. 7.5 cm). Accept: real depth / apparent depth = n.

9(a)感應電荷分佈Distribution of induced charges電和磁 / 靜電學Electricity and magnetism / Electrostatics2/2
圖像表達Diagrams and graphs待教師校對Teacher review

題目Question paper

圖 9.1 中,兩個相同的導電輕球 P 和 Q 彼此靠近但不接觸,並放在絕緣支架上。兩球最初均不帶電。一支帶負電的塑膠棒靠近 Q,但不接觸球體。Figure 9.1 shows two identical conducting light spheres P and Q placed close together without touching, on insulating stands. Both are initially uncharged. A negatively charged plastic rod is brought close to Q without touching it.

在圖 9.1 畫出 P 和 Q 上的電荷分佈。On Figure 9.1, sketch the distribution of charges on P and on Q.

原題插圖Original question figure

評卷參考Marking reference

兩球均出現電荷分離:P 和 Q 各自的左側帶負電,右側帶正電,如評卷參考原圖所示。兩球互不接觸,亦沒有接觸塑膠棒。Both spheres are polarised: show negative charges on the left and positive charges on the right of each sphere, as in the reference figure. Neither sphere touches the other or the rod.

評卷參考原圖 · 第 62 頁Original marking-scheme figure · page 62

學生作答Student response

本小題以圖像作答,請對照下方原稿。This response is graphical; refer to the original crop below.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
Q 球的電荷分佈Correct distribution of charges on sphere Q: positive charges (+) on the right side (near the rod) and negative charges (-) on the left side.1/1已取得Awarded
P 球的電荷分佈Correct distribution of charges on sphere P: positive charges (+) on the right side (near Q) and negative charges (-) on the left side.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

原系統給予圖像滿分,但電荷符號的清晰度需教師對照裁圖確認。The original system awarded full credit, but the charge symbols should be checked against the crop because legibility was flagged.

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

兩球均出現電荷分離:P 和 Q 各自的左側帶負電,右側帶正電,如評卷參考原圖所示。兩球互不接觸,亦沒有接觸塑膠棒。Both spheres are polarised: show negative charges on the left and positive charges on the right of each sphere, as in the reference figure. Neither sphere touches the other or the rod.

9(b)帶電棒的電荷守恆Charge conservation on the rod電和磁 / 靜電學Electricity and magnetism / Electrostatics1/2
因果解釋Causal explanation

題目Question paper

圖 9.1 中,兩個相同的導電輕球 P 和 Q 彼此靠近但不接觸,並放在絕緣支架上。兩球最初均不帶電。一支帶負電的塑膠棒靠近 Q,但不接觸球體。 塑膠棒保持在圖示位置時,學生用手指短暫觸碰 P,然後移走塑膠棒。Figure 9.1 shows two identical conducting light spheres P and Q placed close together without touching, on insulating stands. Both are initially uncharged. A negatively charged plastic rod is brought close to Q without touching it. While the plastic rod remains in the position shown, a student touches P momentarily with a finger. The plastic rod is removed afterwards.

解釋塑膠棒上的電荷量會否減少。Explain whether the amount of charges on the plastic rod would decrease.

原題插圖Original question figure

評卷參考Marking reference

不會。帶電棒沒有接觸導體,沒有電荷轉移;導體內發生靜電感應。No, it remains unchanged as charging is through induction (without any contact or transfer of charges).

學生作答Student response

No. As plastic rod doesn't earthed.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出棒上電荷量不變State that the charge remains unchanged / No.1/1已取得Awarded
以無接觸/無電荷轉移的感應解釋Reason: charging is through induction / without any contact or transfer of charges.0/1未取得Not awarded

評語與失分分析Feedback and mark-loss analysis

判斷電荷量不變正確,但「沒有接地」不足以解釋沒有電荷轉移。The unchanged charge is correctly identified, but “not earthed” does not establish the absence of charge transfer.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

不會。帶電棒沒有接觸導體,沒有電荷轉移;導體內發生靜電感應。No, it remains unchanged as charging is through induction (without any contact or transfer of charges).

9(c)辨別未知電荷極性Identifying an unknown charge電和磁 / 靜電學Electricity and magnetism / Electrostatics1/2
實驗設計Experimental design

題目Question paper

圖 9.1 中,兩個相同的導電輕球 P 和 Q 彼此靠近但不接觸,並放在絕緣支架上。兩球最初均不帶電。一支帶負電的塑膠棒靠近 Q,但不接觸球體。 塑膠棒保持在圖示位置時,學生用手指短暫觸碰 P,然後移走塑膠棒。Figure 9.1 shows two identical conducting light spheres P and Q placed close together without touching, on insulating stands. Both are initially uncharged. A negatively charged plastic rod is brought close to Q without touching it. While the plastic rod remains in the position shown, a student touches P momentarily with a finger. The plastic rod is removed afterwards.

兩球以尼龍線分別懸掛並相距甚遠,解釋如何用其中一球判斷另一帶電棒的未知極性。The two light spheres are now suspended by nylon threads from fixed supports such that the spheres are far apart from each other. Explain how you would use one of the spheres to test for the unknown polarity of another charged rod.

原題插圖Original question figure

評卷參考Marking reference

將未知帶電棒靠近已知帶正電的 P 球而不接觸;排斥表示棒帶正電,吸引表示棒帶負電。Hold / bring the unknown charged rod near sphere P (which carries positive charges) without touching it. If P is repelled, the rod is positive. If P is attracted, the rod is negative.

學生作答Student response

By previous action, P is positively charged and Q is neutral.
Thus, use P.
If the rod is positive, P repulse. If rod is negative P attracted.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
描述靠近但不接觸的操作Procedure: Hold / bring the unknown charged rod near sphere P (carrying positive charges) without touching it.0/1未取得Not awarded
按排斥/吸引判別極性Observation/Conclusion: If P is repelled, the rod is positive; OR if P is attracted, the rod is negative.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

吸引/排斥的判斷正確,欠「靠近但不接觸」的操作描述。The attraction and repulsion deductions are correct; the procedure should specify bringing the rod near without touching.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

將未知帶電棒靠近已知帶正電的 P 球而不接觸;排斥表示棒帶正電,吸引表示棒帶負電。Hold / bring the unknown charged rod near sphere P (which carries positive charges) without touching it. If P is repelled, the rod is positive. If P is attracted, the rod is negative.

10(a)能量守恆實驗Energy-conservation experiment力和運動 / 功、能量和動量Force and motion / Work, energy and momentum3/4
實驗設計Experimental design待教師校對Teacher review

題目Question paper

圖 10.1 中,一條不可伸長的細繩下端連接小金屬球,上端 O 固定在支架上。量角器固定於支架,位於細繩後方。In Figure 10.1, one end of an inextensible string is attached to a small metal ball and its upper end O is fixed to a stand. A protractor is fixed to the stand behind the string.

寫出使用圖示裝置驗證能量守恆的實驗步驟。Write down the steps that you would take to demonstrate the conservation of energy using the set-up given.

原題插圖Original question figure

評卷參考Marking reference

記錄初始非零角度;保持繩拉緊並由靜止釋放;量度另一側最高角度;比較兩側角度/高度,以檢驗機械能守恆。1. Use protractor to mark a specific measurable angle. 2. Release ball from rest with string taut. 3. Measure angle at highest point on the other side (or observe if it swings back to original position). 4. Compare initial and final angles; equality implies conservation of mechanical energy.

學生作答Student response

Place the small metal ball at 0° of protractor with the string straight.
Release the ball and record the maximum degree that ball can reach at another side of protractor.
Repeat the experiment at different degree.

Note that ball must reach the other side with same degree (i.e. degree ) as released.

Thus, Potential energy of ball is conserved.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
記錄明確初始非零角度Use the protractor to measure or mark a specific angle at which the ball is released (measurable and recorded).0/1未取得Not awarded
繩拉緊並由靜止釋放Hold the ball at the marked angle and release it from rest with the string taut.1/1已取得Awarded
量度另一側最高角度Measure the angle at which the ball reaches its highest point (or observe if it swings back to original position).1/1已取得Awarded
比較角度/高度以檢驗能量守恆Compare initial and final angles; equality implies total mechanical energy is conserved.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

已寫釋放、量度另一側角度及比較,初始非零角度的設定不夠明確。Release, measurement of the opposite angle and comparison are described. The initial non-zero release angle is insufficiently specified.

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

記錄初始非零角度;保持繩拉緊並由靜止釋放;量度另一側最高角度;比較兩側角度/高度,以檢驗機械能守恆。1. Use protractor to mark a specific measurable angle. 2. Release ball from rest with string taut. 3. Measure angle at highest point on the other side (or observe if it swings back to original position). 4. Compare initial and final angles; equality implies conservation of mechanical energy.

10(b)(i)(I)碰撞方向的動量守恆Momentum along the collision direction力和運動 / 功、能量和動量Force and motion / Work, energy and momentum1/1
因果解釋Causal explanation

題目Question paper

圖 10.2 的牛頓擺由五個相同金屬球組成,各球由等長、不可伸長的輕繩懸掛在固定水平支架上。A 和 B 一起稍微向左移並從靜止釋放。碰撞後,A 和 B 停下,而 D 和 E 一起稍微向右擺動。忽略空氣阻力。The Newton’s cradle in Figure 10.2 consists of five identical metal spheres suspended in a row by equal-length, inextensible light strings from a fixed horizontal support. A and B are displaced slightly to the left together and released from rest. Just after collision, A and B stop while D and E swing slightly to the right together. Neglect air resistance.

雖然繩張力是外力,解釋為何此碰撞仍可應用動量守恆定律。Even though the tensions in the strings acting on the spheres are external forces, explain why the law of conservation of momentum can still be applied for this collision.

原題插圖Original question figure

評卷參考Marking reference

張力與碰撞方向垂直,在水平方向沒有淨外力/外衝量,故水平方向動量守恆。The tension forces are vertical / perpendicular to the direction of collision, so no external forces act along the colliding / horizontal direction, allowing the law of conservation of momentum to be applied. (Or: tensions are balanced by weights, net force is zero).

學生作答Student response

As the direction of tension and the direction of collision is perpendicular to each other.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出張力與碰撞方向垂直Explain that tension is perpendicular to the horizontal motion (no external horizontal force) OR net force on the system is zero (tensions balanced by weights).1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

正確指出張力與碰撞方向互相垂直。The answer correctly states that tension is perpendicular to the collision direction.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

張力與碰撞方向垂直,在水平方向沒有淨外力/外衝量,故水平方向動量守恆。The tension forces are vertical / perpendicular to the direction of collision, so no external forces act along the colliding / horizontal direction, allowing the law of conservation of momentum to be applied. (Or: tensions are balanced by weights, net force is zero).

10(b)(i)(II)牛頓搖籃的能量檢驗Energy test for Newton’s cradle力和運動 / 功、能量和動量Force and motion / Work, energy and momentum2/3
綜合推論Integrated reasoning

題目Question paper

圖 10.2 的牛頓擺由五個相同金屬球組成,各球由等長、不可伸長的輕繩懸掛在固定水平支架上。A 和 B 一起稍微向左移並從靜止釋放。碰撞後,A 和 B 停下,而 D 和 E 一起稍微向右擺動。忽略空氣阻力。The Newton’s cradle in Figure 10.2 consists of five identical metal spheres suspended in a row by equal-length, inextensible light strings from a fixed horizontal support. A and B are displaced slightly to the left together and released from rest. Just after collision, A and B stop while D and E swing slightly to the right together. Neglect air resistance.

兩球 A、B 各以 0.50 m s⁻¹ 碰撞,每球質量 0.020 kg。假設只有 E 球離開,求其速率,並據此解釋為何這情況不可能發生。Suppose that only one sphere (E) swings to the right with speed vE just after collision. By finding vE and hence explain why it is not possible for only one sphere to swing to the right. Given that the speed of sphere A and B just before collision is 0.50 m s^-1. The mass of each sphere is 0.020 kg.

原題插圖Original question figure

評卷參考Marking reference

2m(0.50) = mvE,vE = 1.0 m s⁻¹。初動能 0.005 J,假設的末動能 0.010 J,末動能較大,故不可能只有 E 以該速率離開。By conservation of momentum, vE = 1.0 m/s. Final KE = 0.01 J. Initial KE = 0.005 J. Since final KE > initial KE, it is not possible.

學生作答Student response

p_AB = p_E
(0.02 × 2)(0.5) = (0.02) v_E
v_E = 1 m s⁻¹

KE_AB = ½ (0.02 × 2)(0.5)² = 5 × 10⁻³ J
KE_E = ½ (0.02)(1)² = 0.01 J ≠ KE_AB
if only one ball out, energy of system does not conserved.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
用動量守恆求 vECalculate final velocity using conservation of momentum: vE = 2 * 0.50 = 1.0 m/s.1/1已取得Awarded
計算初、末動能Calculate final KE (0.01 J) and compare with initial KE (0.005 J).1/1已取得Awarded
指出末動能較大,故假設不可能Conclude that final KE > initial KE, which is impossible.0/1未取得Not awarded

評語與失分分析Feedback and mark-loss analysis

動量和動能計算正確;還需明確指出末動能大於初動能,所以假設不可能。The momentum and energy calculations are correct. The conclusion should explicitly state that the proposed final energy is greater than the initial energy.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

2m(0.50) = mvE,vE = 1.0 m s⁻¹。初動能 0.005 J,假設的末動能 0.010 J,末動能較大,故不可能只有 E 以該速率離開。By conservation of momentum, vE = 1.0 m/s. Final KE = 0.01 J. Initial KE = 0.005 J. Since final KE > initial KE, it is not possible.

10(b)(ii)碰撞的彈性Elasticity of collisions力和運動 / 功、能量和動量Force and motion / Work, energy and momentum1/2
因果解釋Causal explanation

題目Question paper

圖 10.2 的牛頓擺由五個相同金屬球組成,各球由等長、不可伸長的輕繩懸掛在固定水平支架上。A 和 B 一起稍微向左移並從靜止釋放。碰撞後,A 和 B 停下,而 D 和 E 一起稍微向右擺動。忽略空氣阻力。The Newton’s cradle in Figure 10.2 consists of five identical metal spheres suspended in a row by equal-length, inextensible light strings from a fixed horizontal support. A and B are displaced slightly to the left together and released from rest. Just after collision, A and B stop while D and E swing slightly to the right together. Neglect air resistance.

碰撞持續一段時間後整套裝置停止,討論碰撞是否完全彈性。The collision repeats alternately from either side for a period of time before the system eventually returns to a rest. Discuss whether the collisions are perfectly elastic.

原題插圖Original question figure

評卷參考Marking reference

不完全彈性。部分動能轉化為內能及聲能,所以總動能不守恆。Not perfectly elastic as some kinetic energy is lost as sound / thermal energy, so total kinetic energy is not conserved.

學生作答Student response

No. As external force act on the system (i.e. air resistance) then eventually returns to rest.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出不完全彈性State that the collision is not perfectly elastic.1/1已取得Awarded
指出碰撞時動能轉化為聲能/內能Reason: kinetic energy is lost as sound / thermal energy (KE not conserved).0/1未取得Not awarded

評語與失分分析Feedback and mark-loss analysis

「不完全彈性」判斷正確;以空氣阻力解釋未直接回應碰撞中的動能轉化。The collision is correctly identified as not perfectly elastic. Air resistance alone does not explain energy conversion during the collision.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

不完全彈性。部分動能轉化為內能及聲能,所以總動能不守恆。Not perfectly elastic as some kinetic energy is lost as sound / thermal energy, so total kinetic energy is not conserved.

11(a)金屬箔的電阻變化Resistance of stretched foil電和磁 / 電阻與電路Electricity and magnetism / Resistance and circuits0/2
因果解釋Causal explanation待教師校對Teacher review

題目Question paper

閱讀以下有關形變感應器的資料。圖 11.1(a) 的簡單感應裝置由固定在塑膠底板上的薄、平、長方形金屬箔組成。長度為 l、闊度為 w 的金屬箔受拉伸後,如圖 11.1(b) 般變形,電阻因而改變。把装置接至合適電路,即可藉電路參數(例如電壓)的變化監測形變。Read the following information about deformation sensors. Figure 11.1(a) shows a simple sensing device made of thin, flat rectangular metal foil attached to a plastic backing plate. When the foil, of length l and width w, is stretched as in Figure 11.1(b), its resistance changes. Connected to a suitable circuit, the device monitors deformation through changes in circuit parameters such as voltage.

金屬箔被拉長,厚度及電阻率不變。指出並解釋 XY 之間的電阻如何改變。Referring to Figure 11.1(a) and (b), state and explain how the metal foil's resistance across XY changes when the foil is stretched. Assume that the thickness and resistivity of the foil remain unchanged.

原題插圖Original question figure

評卷參考Marking reference

R = ρl/A;l 增加,闊度減少令 A 減少,所以 R 增加。As the foil becomes longer / l increases while its cross-sectional area becomes smaller / A decreases due to decrease in width w, its resistance would increase according to R = ρl/A.

學生作答Student response

[Crossed out: R = ρ l / A]

R ∝ l
When foil is stretched, length XY increase.
∴ Resistance increase.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
同時指出長度增加及截面積減少State that the foil becomes longer (l increases) and the cross-sectional area becomes smaller (A decreases) due to decrease in width w.0/1未取得Not awarded
根據 R = ρl/A 解釋電阻增加State that resistance increases according to the relation R = ρl/A.0/1未取得Not awarded

評語與失分分析Feedback and mark-loss analysis

已指出長度及電阻增加,但未討論橫截面積減少。原判 0/2 的部分給分待校對。Increasing length and resistance are stated, but decreasing cross-sectional area is omitted. Partial credit within the original 0/2 needs checking.

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

R = ρl/A;l 增加,闊度減少令 A 減少,所以 R 增加。As the foil becomes longer / l increases while its cross-sectional area becomes smaller / A decreases due to decrease in width w, its resistance would increase according to R = ρl/A.

11(b)(i)串聯支路的電壓Voltage across a series branch電和磁 / 電阻與電路Electricity and magnetism / Resistance and circuits1/1
公式與運算Formulae and calculation

題目Question paper

圖 11.2 的電路有四個電阻 R₁、R₂、R₃、R₄,接至輸入電壓 Vᵢₙ。Vₒᵤₜ 是 DB 兩點間的電壓。The circuit in Figure 11.2 has four resistors R₁, R₂, R₃ and R₄ connected to an input voltage Vᵢₙ. Vₒᵤₜ is the voltage across DB.

電流 I₁ 流經支路 ABC,寫出 Vᵢₙ、I₁、R₁、R₂ 的關係式。Current I1 flows through branch ABC. Write an equation relating Vin, I1, R1 and R2.

原題插圖Original question figure

評卷參考Marking reference

Vᵢₙ = I₁(R₁ + R₂)。Vin = I1(R1 + R2)

學生作答Student response

V_in = I₁ (R₁ + R₂)

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
寫出 Vᵢₙ = I₁(R₁+R₂)Correct expression for Vin in terms of I1, R1, and R2.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

已正確建立串聯支路的電壓關係。The voltage equation for the series branch is correct.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

Vᵢₙ = I₁(R₁ + R₂)。Vin = I1(R1 + R2)

11(b)(ii)電橋輸出的百分比變化Percentage change in bridge output電和磁 / 電阻與電路Electricity and magnetism / Resistance and circuits1/2
公式與運算Formulae and calculation

題目Question paper

圖 11.2 的電路有四個電阻 R₁、R₂、R₃、R₄,接至輸入電壓 Vᵢₙ。Vₒᵤₜ 是 DB 兩點間的電壓。The circuit in Figure 11.2 has four resistors R₁, R₂, R₃ and R₄ connected to an input voltage Vᵢₙ. Vₒᵤₜ is the voltage across DB.

R₄ 由 500 Ω 增至 501 Ω;其餘三個電阻均為 470 Ω。求 Vₒᵤₜ/Vᵢₙ 的百分比變化。R4 in the circuit is the sensing device described in the passage, with unstretched resistance 500 Ω. Find the corresponding percentage change in Vout/Vin when R4 increases 0.2% (i.e. becomes 501 Ω). Given: Vout/Vin = R4/(R3+R4) - R2/(R1+R2); R1 = R2 = R3 = 470 Ω.

原題插圖Original question figure

評卷參考Marking reference

原比值 = 500/970 − 1/2 ≈ 0.0154639;新比值 = 501/971 − 1/2 ≈ 0.0159629;增加約 3.23%。Before: Vout/Vin = R4/(R3+R4) - R2/(R1+R2) = 500/(470+500) - 470/(470+470) = 0.0154639. After: Vout/Vin = 501/(470+501) - 470/(470+470) = 0.0159629. Percentage increase ≈ 3.23%.

學生作答Student response

( V_out / V_in )' = 501 / (470 + 501) - 470 / (470 + 470)

V_out / V_in = 500 / (470 + 500) - 470 / (470 + 470)

% Δ V_out / V_in = [ ( V_out / V_in )' - V_out / V_in ] / ( V_out / V_in ) × 100%
= 0.0972%

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
代入前後兩個電壓比值Substitution of values into the potential divider/bridge ratio formula for both 'before' and 'after' states.1/1已取得Awarded
得到增加約 3.23%Calculate the percentage increase as approximately 3.23% (Accept range 3.2 to 3.23%).0/1未取得Not awarded

評語與失分分析Feedback and mark-loss analysis

新舊電壓比值的列式正確,但百分比運算結果有誤。The before-and-after voltage ratios are set up correctly, but the calculated percentage change is wrong.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

原比值 = 500/970 − 1/2 ≈ 0.0154639;新比值 = 501/971 − 1/2 ≈ 0.0159629;增加約 3.23%。Before: Vout/Vin = R4/(R3+R4) - R2/(R1+R2) = 500/(470+500) - 470/(470+470) = 0.0154639. After: Vout/Vin = 501/(470+501) - 470/(470+470) = 0.0159629. Percentage increase ≈ 3.23%.

11(b)(iii)(I)裂紋增長的判讀Identifying the growing crack電和磁 / 電阻與電路Electricity and magnetism / Resistance and circuits1/1
審題與判斷Reading and judgement

題目Question paper

感應器 S₁、S₂、S₃、S₄ 接至合適電路並固定在天花 ABCD,如圖 11.3 所示,以監測裂縫 ①、②、③ 的增長。數星期後,偵測到的形變程度依次為 S₁ > S₂ > S₃ > S₄。Sensors S₁, S₂, S₃ and S₄, connected to a suitable circuit, are attached to ceiling ABCD as in Figure 11.3 to monitor cracks ①, ② and ③. After a few weeks, the detected deformation is in the order S₁ > S₂ > S₃ > S₄.

推斷裂紋 ①、②、③ 中哪一道增長最多。Deduce which crack (1, 2 or 3) has grown the most.

原題插圖Original question figure

評卷參考Marking reference

裂紋 ①。crack ①

學生作答Student response

①

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出裂紋 ①Identify crack ① as the cause.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

正確選出裂紋 ①。Crack ① is correctly identified.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

裂紋 ①。crack ①

11(b)(iii)(II)伸展方向Direction of stretching電和磁 / 電阻與電路Electricity and magnetism / Resistance and circuits0/1
審題與判斷Reading and judgement

題目Question paper

感應器 S₁、S₂、S₃、S₄ 接至合適電路並固定在天花 ABCD,如圖 11.3 所示,以監測裂縫 ①、②、③ 的增長。數星期後,偵測到的形變程度依次為 S₁ > S₂ > S₃ > S₄。Sensors S₁, S₂, S₃ and S₄, connected to a suitable circuit, are attached to ceiling ABCD as in Figure 11.3 to monitor cracks ①, ② and ③. After a few weeks, the detected deformation is in the order S₁ > S₂ > S₃ > S₄.

推斷天花板最可能沿 AB、BC 或 AC 哪個方向伸展。Deduce the most probable stretching direction (AB, BC or AC) along the ceiling.

原題插圖Original question figure

評卷參考Marking reference

沿 AB 方向。along AB

學生作答Student response

AC

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出方向 ABIdentify the direction as along AB.0/1未取得Not awarded

評語與失分分析Feedback and mark-loss analysis

原答 AC 與參考方向 AB 不符。The selected direction AC does not match the reference direction AB.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

沿 AB 方向。along AB

12(a)圓形線圈的磁場Field of a circular coil電和磁 / 電磁感應Electricity and magnetism / Electromagnetic induction2/2
圖像表達Diagrams and graphs待教師校對Teacher review

題目Question paper

圖 12.1 顯示一個數匝線圈,電流 I 的方向如圖所示。Figure 12.1 shows a coil of several turns carrying a current I in the direction shown.

按圖示電流方向,畫出圓形線圈所產生的磁場圖樣。Sketch the magnetic field pattern produced by the coil when it carries a current I as shown.

原題插圖Original question figure

評卷參考Marking reference

畫出穿過線圈的磁場圖樣,箭頭方向如參考圖般向下。評卷參考亦接受因對電流方向有不同理解而畫出的向上箭頭;評分分別考慮方向及磁場圖樣。Show the magnetic field pattern through the coil, with arrows downwards as in the reference figure. The marking scheme also accepts upward arrows for a different interpretation of the current direction; award for the correct direction and the correct field pattern.

評卷參考原圖 · 第 65 頁Original marking-scheme figure · page 65

學生作答Student response

本小題以圖像作答,請對照下方原稿。This response is graphical; refer to the original crop below.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
磁力線圖樣正確Correct field pattern: closed loops around the coil wires and lines passing through the center of the coil.1/1已取得Awarded
線圈中心磁場方向正確Correct direction: arrows on field lines point downwards through the center of the coil (also accept field lines pointing upwards for observers with different perception of current direction).1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

磁力線圖樣及中心方向取得兩分。The field-line pattern and direction through the centre receive both marks.

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

畫出穿過線圈的磁場圖樣,箭頭方向如參考圖般向下。評卷參考亦接受因對電流方向有不同理解而畫出的向上箭頭;評分分別考慮方向及磁場圖樣。Show the magnetic field pattern through the coil, with arrows downwards as in the reference figure. The marking scheme also accepts upward arrows for a different interpretation of the current direction; award for the correct direction and the correct field pattern.

12(b)(i)接收線圈的感應電壓Induced voltage in the receiver電和磁 / 電磁感應Electricity and magnetism / Electromagnetic induction2/2
因果解釋Causal explanation

題目Question paper

圖 12.2(a) 中,線圈接至交流電源作為發射線圈 T。連接陰極射線示波器(CRO)的接收線圈 R 放在 T 正上方。圖 12.2(b) 顯示 R 的電壓隨時間的變化。In Figure 12.2(a), the coil is connected to an a.c. source as transmitter coil T. A receiver coil R connected to a cathode-ray oscilloscope (CRO) is placed directly above T. Figure 12.2(b) displays the time variation of R’s voltage.

解釋接收線圈 R 的電壓如何產生。Explain how the voltage of the receiver coil R is produced.

原題插圖Original question figure

評卷參考Marking reference

發射線圈的交流電產生改變的磁場/磁通,接收線圈因電磁感應產生電動勢。The a.c. flowing in transmitter coil T generates a changing magnetic field, thus by electromagnetic induction an induced e.m.f. is produced in receiver coil R to oppose the changing magnetic flux experienced by it.

學生作答Student response

As coil T is connected to an a.c., current is induced in coil R due to changing of B-field from T.
Thus, voltage is induced in R.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出交流電產生改變的磁場The a.c. flowing in transmitter coil T generates a changing magnetic field.1/1已取得Awarded
指出磁通改變產生感應電動勢By electromagnetic induction, an induced e.m.f. is produced in receiver coil R to oppose the changing magnetic flux.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

已指出交流電令磁場改變,從而在接收線圈產生感應電壓。The explanation links alternating current to changing magnetic flux and induced voltage in the receiving coil.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

發射線圈的交流電產生改變的磁場/磁通,接收線圈因電磁感應產生電動勢。The a.c. flowing in transmitter coil T generates a changing magnetic field, thus by electromagnetic induction an induced e.m.f. is produced in receiver coil R to oppose the changing magnetic flux experienced by it.

12(b)(ii)頻率加倍後的波形Waveform after doubling frequency電和磁 / 電磁感應Electricity and magnetism / Electromagnetic induction1/2
圖像表達Diagrams and graphs待教師校對Teacher review

題目Question paper

圖 12.2(a) 中,線圈接至交流電源作為發射線圈 T。連接陰極射線示波器(CRO)的接收線圈 R 放在 T 正上方。圖 12.2(b) 顯示 R 的電壓隨時間的變化。In Figure 12.2(a), the coil is connected to an a.c. source as transmitter coil T. A receiver coil R connected to a cathode-ray oscilloscope (CRO) is placed directly above T. Figure 12.2(b) displays the time variation of R’s voltage.

交流電源的頻率加倍,在圖上畫出新的示波器波形。On Figure 12.2(b), sketch the CRO display when the frequency of the a.c. source is doubled.

原題插圖Original question figure

評卷參考Marking reference

週期減半、頻率加倍;發射電流振幅不變時,磁通改變率加倍,感應電壓振幅亦加倍。The period is halved (frequency doubled). With unchanged transmitter-current amplitude, the induced-voltage amplitude doubles because the rate of change of magnetic flux doubles.

評卷參考原圖 · 第 65 頁Original marking-scheme figure · page 65

學生作答Student response

本小題以圖像作答,請對照下方原稿。This response is graphical; refer to the original crop below.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
週期減半/頻率加倍Correct frequency: the wave shows double the frequency (frequency doubled).1/1已取得Awarded
感應電壓振幅加倍Correct amplitude: the wave shows the correct amplitude relative to the original signal.0/1未取得Not awarded

評語與失分分析Feedback and mark-loss analysis

新波形頻率加倍正確,振幅仍維持原值,未表示感應電壓加倍。The frequency is correctly doubled, but the amplitude is unchanged rather than doubled.

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

週期減半、頻率加倍;發射電流振幅不變時,磁通改變率加倍,感應電壓振幅亦加倍。The period is halved (frequency doubled). With unchanged transmitter-current amplitude, the induced-voltage amplitude doubles because the rate of change of magnetic flux doubles.

12(c)非金屬背蓋與渦流Non-metallic covers and eddy currents電和磁 / 電磁感應Electricity and magnetism / Electromagnetic induction0/2
因果解釋Causal explanation

題目Question paper

手機內置接收線圈,可放在充電板上作無線充電。充電板內置發射線圈,並連接電源。A mobile phone with a receiver coil inside can be charged wirelessly on a charging pad containing a transmitter coil connected to a power source.

解釋無線充電手機為何需要非金屬背蓋。Explain why wirelessly charging of phones need phone cases with non-metallic back covers.

原題插圖Original question figure

評卷參考Marking reference

金屬背蓋會產生渦流,導致發熱/能量損耗或削弱磁通。非金屬絕緣背蓋可避免渦流,讓磁場有效穿過。If the back cover is metallic, eddy currents will be produced (by induction), loss of energy / heating effect results / magnetic field / flux is blocked by the metal case and thus making wireless charging impossible. OR Non-metallic materials such as glass are insulators, and no eddy currents are produced. As a result, energy loss / heating effect will be minimized / the magnetic field can pass through the back cover easily.

學生作答Student response

As principle of wirelessly charging is to induce current
thus voltage on a electrical conduction metal i.e. cell.
Thus, non-metallic back covers will not disturb the effect of induction.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出金屬中產生渦流Metallic cover leads to eddy currents (by induction) OR Non-metallic materials (glass) are insulators and no eddy currents are produced.0/1未取得Not awarded
指出發熱/能量損耗或削弱磁通Eddy currents cause energy loss/heating/blocking of flux making charging impossible OR lack of eddy currents minimizes energy loss and allows magnetic field to pass.0/1未取得Not awarded

評語與失分分析Feedback and mark-loss analysis

未提到渦流及其發熱/阻擋磁通效應,解釋不夠具體。The explanation does not identify eddy currents and their heating or magnetic-shielding effects.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

金屬背蓋會產生渦流,導致發熱/能量損耗或削弱磁通。非金屬絕緣背蓋可避免渦流,讓磁場有效穿過。If the back cover is metallic, eddy currents will be produced (by induction), loss of energy / heating effect results / magnetic field / flux is blocked by the metal case and thus making wireless charging impossible. OR Non-metallic materials such as glass are insulators, and no eddy currents are produced. As a result, energy loss / heating effect will be minimized / the magnetic field can pass through the back cover easily.

13(a)(i)半衰期與衰變常數Half-life and decay constant放射現象和核能 / 放射衰變Radioactivity and nuclear energy / Radioactive decay2/2
公式與運算Formulae and calculation

題目Question paper

氡(Rn-222)是無色、無臭、無味的放射性氣體,從地下基岩或含花崗岩的混凝土釋出。Rn-222 以半衰期 3.82 日放出 α 粒子而衰變。Radon (Rn-222) is a radioactive gas with no colour, smell or taste, released from underground bedrock or concrete containing granite. It decays by emitting α particles with a half-life of 3.82 days.

氡-222 的半衰期為 3.82 日。求其衰變常數,單位為 s⁻¹。Find the decay constant (unit: s^-1) of Rn-222.

評卷參考Marking reference

k = ln 2/(3.82 × 24 × 3600) ≈ 2.10 × 10⁻⁶ s⁻¹。k = ln 2 / t_{1/2} = ln 2 / (3.82 * 24 * 3600) = 2.10 * 10^-6 s^-1

學生作答Student response

k = ln 2 / (3.82 × 24 × 60 × 60)
= 2.10 × 10⁻⁶ s⁻¹

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
以秒為單位代入半衰期公式Substitution: k = ln 2 / (3.82 * 24 * 3600)1/1已取得Awarded
得到 2.10 × 10⁻⁶ s⁻¹Answer: 2.10 * 10^-6 s^-1 (accept 2.1001405 * 10^-6)1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

已把日換成秒,衰變常數的公式及數值正確。The half-life is converted from days to seconds and used correctly.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

k = ln 2/(3.82 × 24 × 3600) ≈ 2.10 × 10⁻⁶ s⁻¹。k = ln 2 / t_{1/2} = ln 2 / (3.82 * 24 * 3600) = 2.10 * 10^-6 s^-1

13(a)(ii)活度與原子數Activity and number of atoms放射現象和核能 / 放射衰變Radioactivity and nuclear energy / Radioactive decay1/2
公式與運算Formulae and calculation待教師校對Teacher review

題目Question paper

氡(Rn-222)是無色、無臭、無味的放射性氣體,從地下基岩或含花崗岩的混凝土釋出。Rn-222 以半衰期 3.82 日放出 α 粒子而衰變。Radon (Rn-222) is a radioactive gas with no colour, smell or taste, released from underground bedrock or concrete containing granite. It decays by emitting α particles with a half-life of 3.82 days.

室內每立方米空氣因氡氣產生的平均活度為 48 Bq。估算每立方米的氡原子數。Inside buildings, the average activity due to radon in 1 m^3 of air is about 48 Bq. Estimate the average number of radon atoms in 1 m^3 of air inside buildings.

評卷參考Marking reference

N = A/k = 48/(2.10 × 10⁻⁶) ≈ 2.29 × 10⁷ 個。A = kN => N = 48 / (2.10 * 10^-6) = 2.29 * 10^7

學生作答Student response

A = k N
N = 48 / k
= 2.29 × 10⁷

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
運用 N = A/k 的代入Substitution: N = 48 / (2.10 * 10^-6)0/1未取得Not awarded
得到 2.29 × 10⁷ 個Answer: 2.29 * 10^7 (Accept: 2.28 ~ 2.3 * 10^7)1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

已寫 A = kN、N = 48/k 並得到正確數值。原判因未重寫 k 的數值扣一分,需校對步驟分。The answer contains A = kN, N = 48/k and the correct result. The original system deducted a method mark for not rewriting the value of k; this needs review.

校對提示:請對照題目、評卷參考及作答裁圖確認本題。此處保留原有分數,尚未視為教師最終確認。Review note: check this item against the question, marking reference and response crops. The recorded score is retained and is not presented as a teacher-confirmed final mark.

改善方法與參考寫法Improvement and reference response

訂正時先核對題目要求,再按以下要點補齊:Check the exact demand, then complete the correction using this reference:

N = A/k = 48/(2.10 × 10⁻⁶) ≈ 2.29 × 10⁷ 個。A = kN => N = 48 / (2.10 * 10^-6) = 2.29 * 10^7

13(a)(iii)氡氣的內照射危害Internal exposure to radon放射現象和核能 / 放射衰變Radioactivity and nuclear energy / Radioactive decay2/2
因果解釋Causal explanation

題目Question paper

氡(Rn-222)是無色、無臭、無味的放射性氣體,從地下基岩或含花崗岩的混凝土釋出。Rn-222 以半衰期 3.82 日放出 α 粒子而衰變。Radon (Rn-222) is a radioactive gas with no colour, smell or taste, released from underground bedrock or concrete containing granite. It decays by emitting α particles with a half-life of 3.82 days.

α 粒子的穿透力有限,解釋為何室內氡氣仍會危害人體。Why is indoor radon considered harmful to human although α particles have limited penetrating power?

評卷參考Marking reference

氡氣可隨呼吸進入肺部;α 粒子電離能力強,可損害附近細胞/組織。As radon is a gas that can be inhaled into the lungs of human, the relatively strong ionizing power of alpha particles emitted by decaying radon / radioactive gas might affect the organs / cells nearby.

學生作答Student response

As human inhale radon in indoor is difficult to be sense by normal feeling. As if human inhale it, α-particle has strong ionizing power. Thus harmful to body.

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
指出氡氣可被吸入體內Radon is a gas that can be inhaled into the lungs.1/1已取得Awarded
指出 α 粒子電離能力強,損害細胞Alpha particles have strong ionizing power and can damage organs/cells nearby.1/1已取得Awarded

評語與失分分析Feedback and mark-loss analysis

已交代吸入氡氣及 α 粒子的強電離能力。Inhalation and the strong ionising power of alpha particles are correctly linked to the risk.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

氡氣可隨呼吸進入肺部;α 粒子電離能力強,可損害附近細胞/組織。As radon is a gas that can be inhaled into the lungs of human, the relatively strong ionizing power of alpha particles emitted by decaying radon / radioactive gas might affect the organs / cells nearby.

13(b)α、β 衰變序列Alpha and beta decay sequence放射現象和核能 / 放射衰變Radioactivity and nuclear energy / Radioactive decay2/2
圖像表達Diagrams and graphs

題目Question paper

Rn-222 屬於以鈾-238(U-238)開始的衰變系列。已知 U-238 依 α、β、β、α 的次序衰變為釷-230(Th-230)。Rn-222 belongs to a decay series starting from uranium-238 (U-238). U-238 decays in the sequence α, β, β, α to form thorium-230 (Th-230).

以箭頭完成 U-238 經 α、β、β、α 衰變至 Th-230 的序列。Rn-222 belongs to a decay series starting from uranium-238 (U-238). It is known that U-238 undergoes decay in the sequence α-β-β-α to become thorium-230 (Th-230). Complete the decay series below from U-238 to Th-230 using arrows.

原題插圖Original question figure

評卷參考Marking reference

U-238 (92,238) → Th-234 (90,234) → Pa-234 (91,234) → U-234 (92,234) → Th-230 (90,230)。依次為 α、β⁻、β⁻、α;本題止於 Th-230。U-238 (Z=92, A=238) → Th-234 (90,234) → Pa-234 (91,234) → U-234 (92,234) → Th-230 (90,230). The changes are α, β⁻, β⁻, α respectively; use directed arrows on the graph.

評卷參考原圖 · 第 66 頁Original marking-scheme figure · page 66

學生作答Student response

238 92 U, 234 90, 91, 92, 230 90

學生原稿裁圖Original student-response crop
評分點Marking point得分Score結果Outcome
四段 α、β⁻、β⁻、α 衰變箭頭的方向及位置正確,終點為 Th-230All four decay arrows have the correct direction and positions: α, β⁻, β⁻, α, ending at Th-230.2/2已取得Awarded

評語與失分分析Feedback and mark-loss analysis

四段 α、β⁻、β⁻、α 衰變箭頭的方向及位置均正確,序列由 U-238 正確連接至 Th-230。All four α, β⁻, β⁻, α decay arrows have the correct direction and positions, correctly linking U-238 to Th-230.

改善方法與參考寫法Improvement and reference response

可延續本題的作答方法,並用以下要點作最後核對:Keep this approach and use the following reference for a final check:

U-238 (92,238) → Th-234 (90,234) → Pa-234 (91,234) → U-234 (92,234) → Th-230 (90,230)。依次為 α、β⁻、β⁻、α;本題止於 Th-230。U-238 (Z=92, A=238) → Th-234 (90,234) → Pa-234 (91,234) → U-234 (92,234) → Th-230 (90,230). The changes are α, β⁻, β⁻, α respectively; use directed arrows on the graph.

圖像檢視 / Image viewer