Multiple-Choice Killing Techniques for IGCSE CIE Physics | IGCSE CIE 物理：选择题秒杀技巧

📚 Multiple-Choice Killing Techniques for IGCSE CIE Physics | IGCSE CIE 物理：选择题秒杀技巧

Multiple-choice questions (MCQs) in IGCSE CIE Physics Paper 2 may seem straightforward, but they are designed to test your understanding, not just recall. With 40 questions to answer in 45 minutes, you need both speed and accuracy. This article reveals high-impact strategies to slash through tricky options and boost your score, turning you into a MCQ-killing machine.

IGCSE CIE 物理试卷二的选择题看似简单，实则精心设计，考察理解而非死记硬背。要在 45 分钟内完成 40 道题，速度和准确率缺一不可。本文将揭示高效果断的技巧，帮你迅速排除迷惑选项，大幅提升得分，让你成为选择题“杀手”。

1. Scan the Stem and Spot Keywords | 快速扫描题干，锁定关键词

Before diving into options, read the stem and underline words like ‘constant’, ‘frictionless’, ‘at rest’, ‘uniform’, ‘resultant’, ‘directly proportional’. These define the physical scenario and often rule out several options immediately.

在浏览选项前，先读题干并圈出关键词，如“恒定”、“无摩擦”、“静止”、“均匀”、“合”、“成正比”。这些词定义了物理情景，往往能立刻排除多个选项。

Often a question hinges on one word — ‘not’ or ‘except’ — which can flip the answer. Circle it immediately so your brain does not overlook it.

很多题目就靠一个词——“不”或“除外”——翻转答案。立即圈出来，让大脑别忽略它。

For calculation questions, identify what quantity is asked: speed, force, energy, charge? Knowing the target helps you ignore irrelevant data and zero in on the correct formula.

对于计算题，先明确求的是哪个量：速率、力、能量、电荷？锁定目标能帮你忽略无关数据，聚焦正确公式。

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2. Check Units and Dimensional Consistency | 检查单位与量纲一致性

Even without solving, eliminate options with wrong units. If a question asks for energy and an option shows ‘N’ (newton), cross it out. Energy is in joules (J), and N is force.

即使不求解，也可以排除单位错误的选项。如果题目问能量，选项却出现“N”（牛顿），直接划掉。能量单位是焦耳 (J)，而 N 是力。

Use base units: speed is m/s, acceleration m/s², force kg m/s² (N), pressure N/m² or Pa. Quickly scan the units in each option; the odd one out is often a trap.

运用基本单位：速度 m/s，加速度 m/s²，力 kg m/s² 即 N，压强 N/m² 即 Pa。快速扫描每个选项的单位，与众不同的通常是陷阱。

For example, a question about resistivity might list options with Ω m, Ω m⁻¹, Ω m². You recall resistivity unit is Ω m, so choose that instantly without reading further.

例如，关于电阻率的题目，选项可能列出 Ω m, Ω m⁻¹, Ω m²。你记得电阻率单位是Ω m，便可秒选，无需多看。

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3. Slash Out Absurd Answers | 砍掉荒谬答案

Some options violate everyday experience or basic physics. For instance, ‘a metal block heats up faster than water because it has higher specific heat capacity’ — false, metals have lower specific heat capacity, so they heat up and cool down quickly. Discard at once.

有些选项违反日常经验或基础物理。例如，“金属块比水升温快是因为它的比热容更大”——错，金属比热容小所以升温快、冷却也快。立刻排除。

In a circuit, a voltmeter connected in series would give a reading almost equal to the source voltage, but an ammeter in parallel would blow a fuse — these are physically wrong connections. Slash them if they appear in any option.

在电路中，电压表串联会测出接近电源电压，但电流表并联会烧保险——这些都是错误接法。一旦在任何选项中出现就砍掉。

When a question asks ‘which statement about an object moving in a circle at constant speed is correct?’ Options mentioning zero acceleration are absurd because direction changes, so centripetal acceleration exists. Cross them out without hesitation.

当题目问“物体做匀速圆周运动时哪个说法正确”，提到加速度为零的选项就是荒谬的，因为方向不断变化，存在向心加速度。毫不犹豫地划掉。

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4. Use Extreme Cases and Common Sense | 运用极端情况与常识

If a problem involves a variable, push it to an extreme: angle 0° or 90°, mass zero, velocity zero, infinite resistance. See which option survives. The correct option must hold at extremes.

如果题目涉及变量，把它推向极端：角度 0° 或 90°，质量为零，速度为零，电阻无穷大。看哪个选项能成立。正确选项必须在极端情况下依然合理。

For instance, a projectile launched at an angle: maximum range occurs at 45°. If options give ranges for 30° and 60°, both should be equal, so a correct answer might be the one matching that symmetry.

例如，抛射体问题：最大射程出现在 45°。若选项给出 30° 和 60° 的射程，两者应相等，据此可找出符合对称性的正确答案。

In a resistance wire question, if length tends to zero, resistance should tend to zero. So options predicting non-zero resistance for zero length are wrong. Similarly, if cross-sectional area becomes huge, resistance should tend to zero.

在电阻丝问题中，若长度趋近零，电阻应趋近零。因此，预言长度为零时电阻非零的选项错误。同理，截面积极大时电阻趋近零。

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5. Master Graph-Reading Shortcuts | 掌握图表速读捷径

MCQ graphs often test slope, area under graph, or intercepts. For a distance-time graph, slope is speed. An option claiming a curved distance-time graph indicates constant speed is wrong — slope must be constant (straight line).

选择题图表常考斜率、线下面积或截距。距离-时间图中，斜率是速率。若选项说弯曲的距离-时间图表示匀速，则错误——斜率必须恒定（直线）。

In velocity-time graphs, area under graph equals displacement. If the graph is a triangle, the area is ½ × base × height. Even without numbers, you can compare areas visually to decide which object travelled further.

速度-时间图中，图下面积等于位移。若图为三角形，面积为 ½ × 底 × 高。即使没给数字，也可目测比较面积，判断哪个物体移动更远。

Know the shapes: for a fixed resistor at constant temperature, I-V graph is a straight line through origin. For a filament lamp, it curves. A diode only conducts in forward bias. Use shape recognition to match

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