📚 High-Frequency Key Points and Common Mistakes Analysis for Year 10 CIE Physics | Year 10 CIE 物理：高频考点与易错题分析
This article picks out the most frequently tested topics in Year 10 CIE Physics and highlights the typical errors students make, helping you sharpen your exam skills. Each section combines a clear explanation with targeted mistake analysis, so you can turn common pitfalls into marks.
本文梳理了 Year 10 CIE 物理考试中最高频的考点，并重点分析了学生反复出错的地方，帮助你精准提升应试能力。每个小节都配有清晰的知识解析和易错点诊断，让你把常见失分点变成得分机会。
1. Kinematics and Motion Graphs | 运动学与运动图像
Velocity-time graphs are a perennial favourite in CIE assessments. The gradient gives acceleration, and the signed area under the graph gives displacement—not distance, unless the motion is in one direction only.
速度-时间图像是 CIE 命题中永远的热点。斜率表示加速度，图像与时间轴围成的有符号面积代表位移，并非路程，除非物体一直朝单一方向运动。
A classic error occurs when a graph line is horizontal: many students believe the object is stationary, whereas it actually indicates constant velocity. Zero slope on a v-t graph means zero acceleration, not zero speed.
一个经典错误出现在图线水平时：许多学生以为物体静止，实际上它表示的是匀速运动。在 v-t 图中，斜率为零仅表示加速度为零，不表示速度为零。
When converting a distance-time graph to a velocity-time graph, candidates sometimes confuse the shape. For a curved distance-time graph (increasing slope), the corresponding v-t graph is a sloping straight line showing constant acceleration, not another curve.
在将距离-时间图转换为速度-时间图时，考生常混淆图形。如果距离-时间线是斜率不断增大的曲线，对应的 v-t 图应是一条表示恒定加速度的斜直线，而不是另一条曲线。
Another trap: calculating acceleration using change in velocity divided by time but failing to use consistent units, e.g. giving speed in km/h and time in seconds without conversion.
另一个陷阱：用速度变化量除以时间计算加速度时，单位不一致，例如速度用 km/h 而时间用秒，却没有进行换算。
2. Forces and Newton's Laws | 力与牛顿定律
Newton' f Year 10 physics. A common slip is using mass in grams instead of kilograms; the SI unit of force, the newton, demands mass in kg.
牛顿第二定律 (F = m a) 是 Year 10 物理的基石。一个常见疏忽是质量用克而不用千克；力的国际单位牛顿时，质量必须用千克。
When an object moves at constant velocity, the resultant force is zero. Students often assume that a moving object must have a forward resultant force, forgetting that balanced forces produce uniform motion.
当物体匀速运动时，合力为零。学生常误以为运动的物体必定受到向前的合力，忘记了平衡力产生的是匀速运动。
Action-reaction pairs (Newton's Third Law) act on different bodies. A typical exam trap asks for the reaction to the weight of a book on a table; pupils often give the normal contact force, but the true reaction is the gravitational pull exerted by the book on the Earth.
作用力与反作用力（牛顿第三定律）作用在不同物体上。典型的考试陷阱是问桌子上书本所受重力的反作用力；学生常答支持力，但真正的反作用力是书对地球的引力。
Friction always opposes motion or attempted motion. In calculations, forgetting to include friction as a resistive force in the net force equation leads to overestimated acceleration.
摩擦力总是阻碍运动或运动趋势。计算时，忘记在合力方程中把摩擦作为阻力计入，会导致加速度被高估。
3. Momentum and Impulse (Extended) | 动量与冲量（拓展）
Momentum is a vector quantity; its direction must be assigned a positive or negative sign in collision problems. The most frequent mistake is adding momenta algebraically without considering direction, which yields an incorrect conservation equation.
动量是矢量；在碰撞问题中必须规定正负方向。最频繁的出错是将动量简单相加而不考虑方向，导致动量守恒方程完全错误。
Impulse equals change in momentum and is the area under a force-time graph. Learners often treat impulse as force alone, omitting the time factor.
冲量等于动量的变化量，是力-时间图像下的面积。学生常把冲量单纯当做力，忽略了时间因素。
In explosive separations, the total momentum before the event is zero. A common error is to give both fragments the same speed; in reality, the fragment with smaller mass flies off at a higher speed to conserve zero total momentum.
在爆炸分离中，事件前总动量为零。常见错误是认为两个碎片速度相同；实际上，质量较小的碎片会以更高的速度飞出，以保持总动量为零。
When applying the principle of conservation of momentum, pupils sometimes forget to check whether external forces (like friction) are negligible; momentum is conserved only in a closed system.
在应用动量守恒定律时，学生有时忘记检查外力（如摩擦力）是否可忽略；动量只在封闭系统中守恒。
4. Energy, Work and Power | 能量、功与功率
Gravitational potential energy (GPE) change is given by mgh, where h is the vertical height change. A persistent mistake is using slant height along a slope rather than the perpendicular height.
重力势能的变化由 mgh 给出，其中 h 是垂直高度的变化。一个顽固错误是用斜面的坡长代替垂直高度。
Kinetic energy, Ek = ½ m v², depends on the square of speed. When speed doubles, kinetic energy quadruples—a fact often overlooked in comparison questions.
动能 Ek = ½ m v² 与速度的平方成正比。速度加倍时，动能变成四倍——在比较题中这一点经常被忽略。
Efficiency is useful output divided by total input, and it can never exceed 100 %. Pupils sometimes present answers over 100 % without questioning the physical possibility.
效率 = 有用输出 / 总输入，绝不可能超过 100%。学生有时给出超过 100% 的答案却不质疑其物理合理性。
Power is the rate of doing work, measured in watts (J/s). Confusing power with energy is a common slip; for example, stating that a lamp 'uses 60 W of energy' instead of 'uses energy at a rate of 60 W'.
功率是做功的速率，单位为瓦特 (J/s)。混淆功率与能量是常见疏忽；例如，声称一盏灯“消耗 60 瓦能量”，而不是“以 60 瓦的速率消耗能量”。
5. Pressure and Density | 压强与密度
. The depth h is measured vertically from the surface, not along a sloping container wall.
液体压强取决于深度、密度和重力场强度：p = ρ g h。深度 h 是从液面垂直向下测量的，而不是沿倾斜容器壁测量的长度。
A common exam question asks why the pressure at the bottom of a tall, narrow container is the same as in a wide container if the liquid height and density are identical. Many students erroneously believe that the weight of the liquid matters; only the height of the liquid column determines pressure.
常见考题会问：如果液柱高度和密度相同，为什么细高容器底部压强与宽容器相同？很多学生错误地认为液体的重量起作用；实际上只有液柱高度决定压强。
When calculating density, candidates sometimes swap mass and volume in the formula or use mixed units, e.g. mass in grams and volume in cm³ without converting to kg and m³.
计算密度时，考生有时将质量和体积在公式中颠倒，或混用单位，比如质量用克、体积用 cm³，却不按要求折算成 kg 和 m³。
Gas pressure acts in all directions. In manometer questions, a common error is to add or subtract the atmospheric pressure incorrectly when determining the gas pressure from a height difference.
气体压强作用于各个方向。在 U 形管压强计问题中，一个常见错误是根据液面高度差推算气体压强时，错误地加减大气压。
6. Thermal Physics: Specific Heat Capacity and Latent Heat | 热物理学：比热容与潜热
lls you how much energy is needed to raise the temperature of 1 kg of a substance by 1 °C. A frequent mishap is confusing specific heat capacity with heat capacity (which refers to an object, not per unit mass).
比热容 c = Q / (m Δθ) 表示使 1 kg 某物质温度升高 1 °C 所需的能量。常见失误是把比热容和热容（指具体物体，不除以质量）混为一谈。
During a change of state, the temperature remains constant even though energy is supplied. Students often incorrectly label a heating curve's flat section as a period of no energy transfer, whereas it actually shows latent heat being absorbed without temperature rise.
在物态变化期间，即使持续供热，温度仍保持不变。学生常错误地把加热曲线的水平段标注为无能量传递的阶段，而它实际上是在吸收潜热且温度不升高。
Specific latent heat of fusion is generally lower than latent heat of vaporisation for the same substance. Candidates sometimes assign values the wrong way round in calculations.
同种物质的熔解比潜热通常低于汽化比潜热。考生在计算中有时会把这两个数值颠倒。
nt heat, forgetting to check whether the question asks for the energy required to melt and then heat the liquid is a typical multi-step error.
使用潜热方程 E = m L 时，忘记检查题目是否要求先熔化再加热液体，这是一个典型的多步骤计算错误。
7. Waves: Reflection, Refraction and Lenses | 波：反射、折射与透镜
The laws of reflection state that the angle of incidence equals the angle of reflection, and both are measured from the normal, not the mirror surface. Measuring from the wrong reference line is a perennial source of lost marks.
反射定律指出，入射角等于反射角，且这两个角都从法线量起，而不是从镜面量起。从错误的参考线量角是屡见不鲜的失分原因。
/ sin r. A common error is to invert the ratio, particularly when light passes into a denser medium; always place the angle in the incident medium in the numerator for a boundary crossing from vacuum or air.
折射的发生是因为光进入不同介质时速度改变。折射率 n = sin i / sin r。常见错误是把比值颠倒了，尤其是光进入密度更大介质时；对于从真空或空气入射的情况，务必将入射介质中的角度放在分子。
Total internal reflection (TIR) only occurs when light travels from a denser to a less dense medium and the angle of incidence exceeds the critical angle. Many students incorrectly invoke TIR for light entering a denser medium, which is physically impossible.
全内反射只会发生在光从光密介质射向光疏介质且入射角大于临界角时。很多学生错误地认为光进入更密介质时也会发生全内反射，这在物理上是不可能的。
Convex lenses form real, inverted images when the object is beyond the focal point. A typical misinterpretation in ray diagrams is drawing rays that do not actually converge to form an image, or placing the image on the same side as the object.
凸透镜在物体位于焦点之外时成倒立实像。在光路图中，一个典型的误解是画出的光线并没有实际汇聚成像，或是把像画在了物体的同一侧。
8. Electricity: Circuits and Calculations | 电学：电路与计算
Ohm' plugging numbers into the wrong variable slots, especially in multi-step circuit problems.
欧姆定律 (V = I R) 适用于温度恒定的欧姆导体。一个常见的粗心错误是把方程变形为 I = V/R 后，在复杂的多步电路题中把数值代入了错误的变量位。
In series circuits, current is the same everywhere, while voltage divides. In parallel circuits, voltage is the same across each branch, while current divides. Reversing these rules is the single most frequent circuit mistake.
在串联电路中，电流处处相等，电压则分配；在并联电路中，各支路电压相等，电流则分配。把这两条规则记反是电路题中最常见的单一错误。
₁ + R₂)) only for two parallel resistors, but then misapply it to three or more resistors.
计算总电阻时，学生常用乘积求和法 (R = (R₁ × R₂)/(R₁ + R₂)) 只适用于两个并联电阻，却错误地把它套用在三个及以上的并联电阻上。
Potential divider circuits are a high-frequency topic. A typical error is to treat the output voltage as being proportional to the resistance of one resistor without considering the supply voltage and total resistance.
分压电路是高频考点。一个典型错误是认为输出电压与某一个电阻的阻值成正比，却忽略了电源电压和总电阻的作用。
9. Electromagnetic Effects: Motor and Generator | 电磁效应：电动机与发电机
The motor effect (force on a current-carrying conductor in a magnetic field) is governed by Fleming's left-hand rule. Students frequently swap left and right hands, or align their fingers incorrectly with the field (first finger) and current (second finger).
电动机效应（磁场对载流导体的力）由弗莱明左手定则判定。学生时常混淆左右手，或者错误地对齐磁感线方向（食指）和电流方向（中指）。
For the generator effect (electromagnetic induction), the right-hand dynamo rule applies. A common error is to think that a coil must be moving relative to a magnet to induce voltage; a changing magnetic field alone, e.g. from an alternating current in a primary coil, also induces voltage in a stationary secondary coil.
对于发电机效应（电磁感应），适用右手定则。常见错误是认为线圈必须相对磁铁运动才能感应电压；实际上，仅靠变化的磁场，例如初级线圈中的交流电，也能在静止的次级线圈中感应出电压。
The size of the induced e.m.f. depends on the rate of change of magnetic flux linkage. In graph questions showing flux linkage changing with time, candidates often pick the point of maximum flux as the point of maximum induced e.m.f., whereas it is the steepest gradient that gives the peak induced voltage.
感应电动势的大小取决于磁通量变化的快慢。在展示磁通量随时间变化图像的题目中，考生常以为磁通量最大处感应电动势最大，但实际上是图像斜率最陡处对应的感应电压最大。
Lenz's law states that the induced current opposes the change causing it. Students often simply state 'it opposes the motion' without linking the direction of induced current to the pole of the induced magnet.
楞次定律指出，感应电流的方向是阻碍引起它的变化。学生往往只简单地说“阻碍运动”，却不能把感应电流的方向与感应磁极的极性联系起来。
10. Radioactivity and Half-life | 放射性与半衰期
Half-life is the time taken for the activity (or number of undecayed nuclei) of a radioactive sample to fall to half its initial value. A widespread misunderstanding is that half-life means half the atoms have 'disappeared entirely'; in reality, they have decayed into different nuclei.
半衰期是指放射性样品的活度（或未衰变原子核数）减小到初始值一半所需的时间。一种普遍误解是认为半衰期意味着一半的原子“彻底消失”了；事实上，它们衰变成了不同的原子核。
When analysing a half-life graph, always take a reading from the curve, halve it, and read the corresponding time interval. Common exam errors include using linear interpolation instead of the actual curve, or assuming the half-life changes over time (it is constant for a given isotope).
分析半衰期图像时，总是要从曲线上读取一个活度值，取半，再读出对应的时间间隔。常见考试错误是用线性插值代替实际曲线，或误以为半衰期会随时间变化（对特定同位素，半衰期是恒定的）。
Penetrating power: alpha particles are stopped by paper, beta by a few mm of aluminium, and gamma by thick lead or concrete. Pupils sometimes ascribe the wrong penetration to each type, especially confusing beta and gamma shielding.
穿透能力：α 粒子可被纸挡住，β 粒子被几毫米铝片挡住，伽玛射线需厚铅板或混凝土阻挡。学生有时给各个类型张冠李戴穿透力，尤其容易混淆 β 和伽玛的屏蔽材料。
Nuclear equations require conservation of both mass number and proton number. The most frequent slip is failing to balance the proton number when a beta particle is emitted; a neutron changes to a proton, so the atomic number increases by 1, not decreases.
核反应方程式要求质量数和质子数都守恒。最频发的疏忽是在释放 β 粒子时没有平衡质子数；一个中子转变为一个质子，因此原子序数增加 1，而不是减少。
Published by TutorHao | Physics Revision Series | aleveler.com
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