📚 Year 11 CAIE Physics: High-Frequency Topics & Common Pitfalls | Year 11 CAIE 物理：高频考点与易错题分析
This revision guide tackles the topics that appear most frequently in the CAIE IGCSE Physics (0625) exam for Year 11 students. It also highlights the common mistakes that cost marks in Paper 1 (Multiple Choice), Paper 2 (Theory) and Paper 4 (Extended Theory). The content focuses on clear explanations with bilingual notes, worked key equations, and practical tips to avoid typical errors.
本备考指南聚焦 Year 11 学生在 CAIE IGCSE 物理 (0625) 考试中出现频率最高的考点，同时指出那些在 Paper 1（选择题）、Paper 2（理论）与 Paper 4（拓展理论）中容易失分的常见错误。文章采用清晰的双语讲解、关键方程解析以及实用建议，帮助你避开典型陷阱。
1. Motion Graphs and Kinematics Equations | 运动图像与运动学公式
Students frequently misinterpret the slope and area under velocity-time graphs. A velocity-time graph with a positive slope indicates acceleration, and the area between the line and the time axis gives displacement. A flat horizontal line on a velocity-time graph means constant velocity, not the object being at rest.
学生们经常误解速度-时间图上的斜率和面积。速度-时间图上的正斜率代表在加速，而图线与时间轴围成的面积等于位移。速度-时间图上的水平直线表示速度恒定，而不是物体静止。
When using s = ut + ½at², many candidates forget that the acceleration must be constant and they substitute velocity for displacement. Also, sign conventions for direction must be consistent. For an object thrown upwards, acceleration due to gravity is negative when upward velocity is taken as positive.
在使用公式 s = ut + ½at² 时，很多考生忘记加速度必须恒定，而且常常把速度误当作位移代入。另外，方向正负号必须一致。对于竖直上抛运动，若取向上速度为正，那么重力加速度应为负。
v² = u² + 2 a s | v = u + at | s = (u + v)/2 × t
Common mistake: using the average speed formula for non-uniform acceleration or confusing instantaneous speed with average speed from a distance-time graph.
常见错误：用平均速度公式计算非匀加速运动，或者混淆距离-时间图中的瞬时速度与平均速度。
2. Forces, Free-Body Diagrams and Newton’s Third Law | 力、受力分析与牛顿第三定律
A free-body diagram must only show forces acting on the object of interest. Students often include forces the object exerts on its surroundings, which leads to double counting. For example, the weight of a book on a table and the normal reaction force are not an action-reaction pair in the Newton’s third law sense; the pair is the pull of Earth on the book and the pull of the book on Earth.
受力分析图只能画出作用在选定对象上的力。学生经常把该物体施加给周围环境的力也画进去，导致力的重复计算。比如说，放在桌上的书所受的重力与桌面的支持力并非牛顿第三定律中的作用力与反作用力对；真正的作用反作用对是地球对书的引力与书对地球的引力。
Newton’s second law, F = ma, requires the resultant force. Many candidates simply plug in a single applied force without subtracting friction or component forces. Also, when mass is given in grams, convert it to kilograms before using the equation.
牛顿第二定律 F = ma 中使用的是合力。许多考生直接将某个施加的力代入公式，却不减去摩擦力或没考虑力的分解。此外，当质量单位为克时，务必先转换为千克再进行计算。
Fnet = m a
3. Energy Transfers and Efficiency | 能量转化与效率
Gravitational potential energy (GPE) and kinetic energy (KE) conversions are high-frequency topics. The equation ΔEₚ = m g Δh is often misapplied when the change in height is not vertical. Remind yourself that Δh is the vertical height difference, not the distance travelled along a slope.
重力势能 (GPE) 与动能 (KE) 的相互转化是高频考点。公式 ΔEₚ = m g Δh 常被用错，因为高度变化必须沿竖直方向。记住 Δh 是竖直高度差，不是沿着斜面运动的路径长度。
Efficiency calculations cause problems when energy output and input are given in different units, such as joules and kilojoules. Always convert to the same unit, and know that efficiency can never exceed 1 (or 100%).
效率计算出错常因输出能与输入能单位不统一，比如一个是焦耳另一个是千焦耳。务必统一单位，并且要明确效率绝不会大于 1（或 100%）。
Efficiency = Useful energy output / Total energy input
4. Thermal Physics: Specific Heat and Latent Heat | 热物理：比热容与潜热
Candidates often mix up specific heat capacity and specific latent heat. The equation Q = m c Δθ applies when a material changes temperature, while Q = m L is used during a change of state at constant temperature. Applying the specific heat formula during melting is a classic error.
考生常混淆比热容和比潜热。公式 Q = m c Δθ 适用于物体温度改变时，而 Q = m L 用于温度不变的状态变化过程。在熔化过程中使用比热容公式是典型错误。
When interpreting heating curves, the flat sections indicate a change of state (latent heat), not a pause in energy input. The heater is still supplying thermal energy, but the energy is breaking intermolecular bonds instead of raising temperature.
分析加热曲线时，平坦段表示发生了状态变化（潜热阶段），而不是停止了供热。加热器仍然在提供热能，只是这部分能量用于打破分子间作用力，而非升高温度。
5. Wave Properties: v = f λ and Types of Waves | 波的性质：波速公式与波的类型
The wave equation v = f λ is straightforward, but careless unit conversions trip many students. Frequencies in kHz or MHz must be changed to Hz, and wavelengths in cm to m. In ripple tank experiments, the frequency of the wave source remains unchanged when the wave moves into shallow water; only wavelength and speed alter.
波速公式 v = f λ 本身很简单，但单位换算却让许多学生栽跟头。千赫兹（kHz）或兆赫兹（MHz）必须换算成赫兹（Hz），厘米（cm）要换算成米（m）。在水波槽实验中，波从深水区进入浅水区时频率不变，改变的只是波长和波速。
Many exam answers confuse transverse and longitudinal waves. Electromagnetic waves are transverse and can travel through a vacuum, whereas sound waves are longitudinal and require a medium. A common misconception is that all waves need a material medium – electromagnetic waves do not.
很多考试答案分不清横波和纵波。电磁波是横波，可以在真空中传播；而声波是纵波，需要介质。一个常见误解是认为所有波都需要物质介质——电磁波并不需要。
6. Light: Refraction, Lenses and Ray Diagrams | 光：折射、透镜与光路图
When drawing ray diagrams for convex lenses, students frequently place the image on the same side as the object for a real image, or fail to draw a dotted line for a virtual image. A real image is always formed on the opposite side of the lens from the object and can be projected onto a screen.
画凸透镜光路图时，学生经常把实像画在和物体同一侧，或者忘记用虚线表示虚像。实像总是成在透镜的异侧，并且可以投射到屏幕上。
Refraction diagram mistakes include not showing the normal, or drawing the ray bending towards the normal when entering a less dense medium. Remember: from air to glass, the ray bends towards the normal; from glass to air, it bends away. Using Snell’s law, be careful with sines and enter angles in degrees, not radians.
折射图中的错误包括不画法线，或者光线进入较疏介质时画成偏向法线。要记住：从空气到玻璃，光线偏向法线；从玻璃到空气，光线偏离法线。应用斯涅尔定律时，注意正弦值，且角度要用度而不是弧度。
n = sin i / sin r
7. Electricity: Ohm’s Law, Resistance Combinations | 电学：欧姆定律、电阻组合
The relationship V = I R is applied incorrectly when the circuit contains both series and parallel sections. The total resistance of parallel resistors is always less than the smallest individual resistor, a concept often verified by calculation but poorly understood conceptually.
当电路既有串联又有并联部分时，V = I R 的应用容易出错。并联的总电阻总是小于任何一个并联电阻中最小的那个，这个概念虽然常通过计算验证，但学生理解得不深。
Recurrent mistake: assuming the current is the same through components that are in parallel. In a parallel circuit, the potential difference across each branch is the same, but the current splits. In a series circuit, the current is the same everywhere, but the p.d. divides.
重复出现的错误是：以为并联支路的电流处处相等。实际上并联电路中各支路两端的电势差相等，而电流会分流。串联电路则电流处处相等，而电压会分配。
| Series | Parallel |
|---|---|
| Rtotal = R₁ + R₂ + … | 1/Rtotal = 1/R₁ + 1/R₂ + … |
8. Electromagnetism: Motors, Generators and Transformers | 电磁学：电动机、发电机与变压器
Fleming’s left-hand rule (for motors) and right-hand rule (for generators) are frequently swapped. Left-hand rule: the thumb shows motion (force), the first finger shows magnetic field (N to S), and the second finger shows conventional current (+ to -). The right-hand generator rule gives the induced current direction when a conductor moves through a field.
弗莱明左手定则（电动机）和右手定则（发电机）经常被搞混。左手定则：拇指表示运动（受力）方向，食指表示磁场方向(N 到 S)，中指表示传统电流方向（+ 到 -）。右手发电机定则用于判断导体在磁场中运动时感应电流的方向。
Transformer equations require careful ratio handling. Many pupils invert the turns ratio or voltage ratio. For an ideal transformer: Vₚ / Vₛ = Nₚ / Nₛ. If the primary voltage is larger, the transformer is step-down. Remember that transformers only work with alternating current (AC).
变压器方程需要仔细处理比例关系。许多学生会把匝数比或电压比弄反。对于理想变压器：Vₚ / Vₛ = Nₚ / Nₛ。若初级电压更高，该变压器是降压变压器。还要记得变压器只能用于交流电 (AC)。
9. Radioactivity and Half-Life Calculations | 放射性与半衰期计算
Half-life questions are best approached by repeatedly halving the initial count rate or mass until the time elapsed equals the multiple of the half-life. A common error is confusing count rate with number of undecayed nuclei; only the count rate after background subtraction should be used.
半衰期题目最佳的做法是将初始计数率或质量不断减半，直到经过的时间等于半衰期的整数倍。常见错误是混淆计数率与未衰变的原子核数目；应当使用扣除背景辐射后的计数率。
When dealing with gamma emission, candidates sometimes think the mass number or atomic number changes. Gamma radiation is an electromagnetic wave and carries no charge; therefore, the nuclear composition does not change, though the nucleus moves to a lower energy state.
涉及γ 放射时，考生有时以为质量数或原子序数会变。γ 射线是电磁波且不带电，因此原子核组成不变，只是核跃迁到较低能态。
N = N₀ (½)t / T½
10. Experimental Skills: Errors and Data Analysis | 实验技能：误差与数据分析
In Paper 4 and Paper 6 (Alternative to Practical), describing improvements to reduce parallax error, thermal losses, or friction is frequently required. A common source of lost marks is stating that repeating readings makes the experiment 'more accurate'; repeating improves reliability and allows identification of anomalies, while reducing systematic error improves accuracy.
在 Paper 4 和 Paper 6 (实验替代卷) 中，经常要求描述如何减少视差、热量损失或摩擦等实验误差。一个常见的失分原因是说重复读数会使实验“更准确”；重复实验提高的是可靠性、帮助发现异常值，而减少系统误差才能提高准确度。
Reading measuring instruments: when a value lies exactly on a scale mark, candidates often fail to add the appropriate zero. For a metre rule reading at exactly 12.0 cm, writing 12 cm is insufficient; the zero shows the precision of the instrument.
读取测量仪器时，若读数恰好落在刻度线上，考生常忘记补上合适的零。例如直尺读数正好是 12.0 cm 时，写成 12 cm 不够；末尾的零能体现仪器精度。
Published by TutorHao | Physics Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图