📚 IGCSE CCEA Physics: Last-Minute Revision Notes | IGCSE CCEA 物理：考前冲刺笔记
This guide provides a concise summary of the most important concepts, formulas, and tips for the IGCSE CCEA Physics exam. Use it to quickly review key topics and common pitfalls.
本指南为 IGCSE CCEA 物理考试提供了最重要概念、公式和技巧的简明总结，用于快速复习关键主题和常见错误。
1. Key Quantities, Units and Measurement | 关键物理量、单位和测量
A scalar quantity has only magnitude (e.g., mass, distance, speed). A vector quantity has both magnitude and direction (e.g., velocity, displacement, force). Always check if direction matters in an answer.
标量只有大小（如质量、路程、速率）。矢量既有大小又有方向（如速度、位移、力）。答题时务必区分是否需要方向。
All base quantities are measured in SI units: length in metres (m), mass in kilograms (kg), time in seconds (s), electric current in amperes (A), temperature in kelvin (K). Prefixes like kilo (103), milli (10-3) and micro (10-6) must be known for conversions.
基本量均采用国际单位：长度用米(m)，质量用千克(kg)，时间用秒(s)，电流用安培(A)，温度用开尔文(K)。必须掌握千(k,103)、毫(m,10-3)、微(µ,10-6)等词头的换算。
When using measuring instruments, parallax error is reduced by viewing the scale perpendicular to the pointer or meniscus. For micrometers and vernier calipers, remember to check for zero error before taking readings.
使用测量仪器时，视线应与指针或液面凹面垂直以减小视差。使用千分尺和游标卡尺前，务必检查零误差。
2. Motion | 运动
Distance is a scalar measuring the total path length; displacement is a vector measuring the shortest straight-line distance from start to finish. Speed is the rate of change of distance; velocity is the rate of change of displacement.
路程是标量，指运动轨迹的总长度；位移是矢量，指从起点到终点的直线最短距离。速率是路程的变化率；速度是位移的变化率。
On a distance–time graph, the gradient gives speed. On a velocity–time graph, the gradient gives acceleration, and the area under the graph gives displacement. A horizontal line on a v–t graph means constant velocity (zero acceleration).
在路程–时间图上，斜率表示速率。在速度–时间图上，斜率表示加速度，面积表示位移。v–t 图上的水平线表示匀速运动（加速度为零）。
For uniform acceleration in a straight line, use the SUVAT equations. The key formulas are:
v = u + a t
s = u t + ½ a t2
v2 = u2 + 2 a s
s = ½ (u + v) t
These only apply when acceleration ‘a’ is constant. The acceleration of free fall near the Earth’s surface is approximately 9.8 m s-2 (often rounded to 10 m s-2 in CCEA problems).
只适用于加速度恒定的情况。地表附近自由落体加速度 g 约为 9.8 m s-2（CCEA 试题中常取 10 m s-2）。
3. Forces and Newton’s Laws | 力和牛顿定律
Newton’s First Law: An object remains at rest or in uniform motion in a straight line unless acted on by a resultant force. Mass is a measure of inertia.
牛顿第一定律：除非受到合力作用，物体将保持静止或匀速直线运动。质量是惯性的量度。
Newton’s Second Law: Resultant force = mass × acceleration, F = m a. This force must be in newtons (N) when mass is in kg and acceleration in m s-2.
牛顿第二定律：合力 = 质量 × 加速度，F = m a。当质量单位为 kg、加速度单位为 m s-2 时，力单位为牛顿(N)。
Newton’s Third Law: For every action force there is an equal and opposite reaction force. These forces act on different objects, so they do not cancel out for a single object.
牛顿第三定律：每一个作用力都有一个大小相等、方向相反的反作用力。这两个力作用在不同物体上，因此不会相互抵消。
Weight is the gravitational force on an object: W = m g. Always distinguish between mass (kg, scalar) and weight (N, vector). Friction and air resistance oppose motion; the terminal velocity is reached when weight equals air resistance, giving zero resultant force.
重量是物体所受的重力：W = m g。必须区分质量（kg，标量）与重量（N，矢量）。摩擦力和空气阻力阻碍运动；当重力与空气阻力平衡时，合力为零，物体达到终端速度。
4. Momentum | 动量
Momentum is defined as the product of mass and velocity: p = m v. Momentum is a vector quantity and has the unit kg m s-1.
动量定义为质量和速度的乘积：p = m v。动量是矢量，单位是 kg m s-1。
In a closed system, total momentum before a collision or explosion equals total momentum after: m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂. This principle of conservation of momentum is used to solve collision and recoil problems.
在封闭系统中，碰撞或爆炸前的总动量等于总动量：m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂。动量守恒原理用于解决碰撞和反冲问题。
The change in momentum is called impulse: F t = Δp = m v – m u. Increasing the time of impact reduces the force, which explains how crumple zones, air bags and seat belts work to protect passengers.
动量的变化称为冲量：F t = Δp = m v – m u。延长碰撞时间可以减小作用力，这就是安全气囊、安全带和溃缩区的保护原理。
5. Energy, Work and Power | 能量、功和功率
Energy can exist in many forms (kinetic, gravitational potential, thermal, chemical, nuclear, etc.) and is always conserved. Work is done when a force moves an object in the direction of the force: W = F d (unit: joule, J).
能量有多种形式（动能、重力势能、热能、化学能、核能等），且总是守恒的。力使物体沿力的方向移动时做功：W = F d（单位：焦耳，J）。
Kinetic energy: KE = ½ m v2. Gravitational potential energy: GPE = m g h. For a falling object, the loss in GPE equals the gain in KE if air resistance is negligible.
动能：KE = ½ m v2。重力势能：GPE = m g h。忽略空气阻力时，物体下落减少的重力势能等于增加的动能。
Power is the rate of doing work or transferring energy: P = W / t (unit: watt, W). For an object moving at constant speed v against a force F, power can also be calculated as P = F v. Efficiency = useful energy output / total energy input (× 100%).
功率是做功或能量转移的速率：P = W / t（单位：瓦特，W）。物体以恒定速度 v 克服力 F 运动时，也可用 P = F v。效率 = 有用输出能量 / 总输入能量 (× 100%)。
6. Density and Pressure | 密度和压强
Density is mass per unit volume: ρ = m / V. The unit is kg m-3, though g cm-3 is also common. Recall that 1 g cm-3 = 1000 kg m-3.
密度是单位体积的质量：ρ = m / V。单位为 kg m-3，也常用 g cm-3。注意 1 g cm-3 = 1000 kg m-3。
Pressure on a surface is force per unit area: p = F / A (unit: pascal, Pa, where 1 Pa = 1 N m-2). A larger area reduces pressure for a given force, which is why wide tyres prevent sinking.
压强是单位面积上的力：p = F / A（单位：帕斯卡，Pa，1 Pa = 1 N m-2）。给定力时，增大面积可减小压强，因此宽轮胎不易下陷。
In a liquid, pressure increases with depth and density: p = ρ g h. This pressure acts equally in all directions. Atmospheric pressure at sea level is approximately 1.0 × 105 Pa.
液体压强随深度和密度增加：p = ρ g h。液体压强在各个方向上相等。海平面标准大气压约为 1.0 × 105 Pa。
7. Waves | 波动
Waves transfer energy without transferring matter. Transverse waves (e.g., light, water ripples) have oscillations perpendicular to the direction of energy transfer. Longitudinal waves (e.g., sound) have oscillations parallel to the direction of energy transfer.
波传递能量而不传递物质。横波（如光波、水波）的振动方向与能量传播方向垂直。纵波（如声波）的振动方向与能量传播方向平行。
The wave equation links speed (v), frequency (f) and wavelength (λ): v = f λ. Frequency is the number of complete waves per second, measured in hertz (Hz). The period T = 1 / f.
波速公式：v = f λ。频率是每秒完整波的个数，单位为赫兹(Hz)。周期 T = 1 / f。
Reflection, refraction and diffraction are key wave phenomena. Refraction occurs because the speed of the wave changes when it enters a different medium. Diffraction is the spreading of a wave as it passes through a gap or around an obstacle; it is most noticeable when the gap size is approximately equal to the wavelength.
反射、折射和衍射是重要的波动现象。折射是由于波在不同介质中传播速度不同引起的。衍射是波通过狭缝或绕过障碍物时发生的扩展现象；当缝宽与波长相近时衍射最明显。
The electromagnetic spectrum, in order of increasing frequency/decreasing wavelength, is: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays. All travel at the same speed in a vacuum (3.0 × 108 m s-1).
电磁波谱按频率递增/波长递减排列为：无线电波、微波、红外线、可见光、紫外线、X 射线、γ 射线。它们在真空中都以相同速度传播(3.0 × 108 m s-1)。
8. Light and Optics | 光和光学
The law of reflection: the angle of incidence (i) equals the angle of reflection (r), with both measured from the normal. Plane mirrors produce virtual, laterally inverted images.
反射定律：入射角(i)等于反射角(r)，均从法线量起。平面镜产生虚像，且左右颠倒。
Refractive index n describes how much light slows down in a medium: n = sin i / sin r, where i is the angle in a vacuum (or air) and r is the angle in the medium. Snell’s law: n₁ sin θ₁ = n₂ sin θ₂.
折射率 n 描述光在介质中的减速程度：n = sin i / sin r，其中 i 为真空（或空气）中的角度，r 为介质中的角度。斯涅尔定律：n₁ sin θ₁ = n₂ sin θ₂。
Total internal reflection occurs when light travels from a denser medium to a less dense medium at an angle of incidence greater than the critical angle c. The critical angle is given by sin c = 1 / n. This principle is used in optical fibres.
当光从光密介质射向光疏介质且入射角大于临界角 c 时，发生全内反射。临界角由 sin c = 1 / n 给出。光纤利用了这一原理。
Converging (convex) lenses can produce real or virtual images depending on object distance. Use the formula 1 / f = 1 / u + 1 / v (f = focal length, u = object distance, v = image distance). The magnification m = v / u = image height / object height.
会聚透镜（凸透镜）依据物距可成实像或虚像。使用公式 1 / f = 1 / u + 1 / v（f 焦距，u 物距，v 像距）。放大率 m = v / u = 像高 / 物高。
9. Electricity | 电学
Electric current is the rate of flow of charge: I = Q / t (unit: ampere, A). In metals, current is carried by free electrons. Conventional current flows from positive to negative.
电流是电荷流动的速率：I = Q / t（单位：安培，A）。金属中电流由自由电子承载。约定电流方向由正到负。
Potential difference (voltage) is the energy transferred per unit charge: V = W / Q. Resistance is the opposition to current: R = V / I (unit: ohm, Ω). Ohm’s law states that V ∝ I for a resistor at constant temperature.
电势差（电压）是单位电荷转移的能量：V = W / Q。电阻是电流受到的阻碍：R = V / I（单位：欧姆，Ω）。欧姆定律指出，在温度不变时，电阻两端电压与电流成正比。
In series circuits, current is the same everywhere, and the total resistance is the sum of individual resistors: Rtotal = R₁ + R₂ + … In parallel circuits, the total current splits, and the combined resistance is given by 1 / Rtotal = 1 / R₁ + 1 / R₂ + …
串联电路中电流处处相等，总电阻为各电阻之和：R总 = R₁ + R₂ + … 并联电路中总电流分流，总电阻由 1 / R总 = 1 / R₁ + 1 / R₂ + … 计算。
Electrical power P = I V = I2 R = V2 / R. Energy consumed E = P t = I V t. The kilowatt-hour (kW h) is a unit of energy; 1 kW h = 3.6 × 106 J.
电功率 P = I V = I2 R = V2 / R。消耗的电能 E = P t = I V t。千瓦时(kW h)是能量单位；1 kW h = 3.6 × 106 J。
10. Electromagnetism and Radioactivity | 电磁学和放射性
A current-carrying wire in a magnetic field experiences a force (the motor effect) given by F = B I L when the field is perpendicular. Fleming’s left-hand rule predicts force direction. This principle is used in electric motors.
载流导线在磁场中会受到力（电动机效应），当磁场垂直时力为 F = B I L。弗莱明左手定则判定力方向。电动机利用此原理工作。
Electromagnetic induction: when a conductor cuts magnetic field lines, a potential difference is induced. Transformers change alternating voltage: Vp / Vs = np / ns. For an ideal transformer, input power equals output power: Vp Ip = Vs Is.
电磁感应：导体切割磁感线时产生感应电动势。变压器可改变交流电压：Vp / Vs = np / ns。理想变压器输入功率等于输出功率：Vp Ip = Vs Is。
Radioactive decay is a random process where unstable nuclei emit radiation. Alpha particles (α) are helium nuclei (2 protons + 2 neutrons), strongly ionising but weakly penetrating. Beta particles (β) are fast electrons, moderately ionising and penetrating. Gamma rays (γ) are electromagnetic waves, weakly ionising but highly penetrating.
放射性衰变是不稳定核随机发射辐射的过程。α 粒子为氦核(2个质子+2个中子)，电离能力强，穿透力弱。β 粒子为高速电子，电离和穿透能力中等。γ 射线为电磁波，电离能力弱，穿透力极强。
The half-life is the time taken for half the radioactive nuclei in a sample to decay. It is constant for a given isotope. Atomic number (Z) is the proton number; mass number (A) is the total number of protons + neutrons. In nuclear equations, total A and total Z are conserved.
半衰期是指样品中一半放射性原子核发生衰变所需的时间，对特定核素是常数。原子序数 Z 为质子数；质量数 A 为质子加中子数。核反应方程中，总质量数和总原子序数守恒。
Published by TutorHao | Physics Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导