📚 IGCSE Edexcel Physics: End-of-Term Revision Checklist | IGCSE Edexcel 物理：期末复习提纲
This end-of-term revision checklist covers the essential topics in the IGCSE Edexcel Physics syllabus (4PH1). Use it to audit your understanding, then concentrate your remaining study time on the key formulas, definitions, units and graph skills that frequently appear again and again in examinations. Work through each section systematically, tick off what you can already explain without notes, and practise past-paper questions on the topics you cannot. The checklist is designed to be used repeatedly: a first pass to diagnose gaps, a second pass to close them, and a final pass in the last week before the exam for quick recall.
这份期末复习提纲涵盖 IGCSE Edexcel 物理（4PH1）教学大纲的核心主题。用它来排查自己的掌握程度，再把剩余复习时间集中投入在反复出现在考试中的关键公式、定义、单位和图像技能上。请按部就班地梳理每一部分：凡是能脱稿解释的内容就打勾，凡是解释不清的就配合历年真题练习。这份提纲可以反复使用——第一遍用于诊断漏洞，第二遍用于补齐漏洞，考前最后一周再快速过一遍用于记忆唤醒。
1. Units, and Measurement and Vectors | 单位、测量与矢量
in (K) for temperature. Derived units include the newton (N) for force, the pascal (Pa) for pressure, the joule (J) for energy, the watt (W) for power, the coulomb (C) for charge, the volt (V) for potential difference and the ohm (Ω) for resistance. You should be able to express any derived unit in terms of base units, for example 1 N = 1 kg m/s² and 1 Pa = 1 N/m².
确保你能回忆国际单位制基本单位：米（m）表示长度，千克（kg）表示质量，秒（s）表示时间，安培（A）表示电流，开尔文（K）表示温度。导出单位包括牛顿（N）表示力、帕斯卡（Pa）表示压强、焦耳（J）表示能量、瓦特（W）表示功率、库仑（C）表示电荷、伏特（V）表示电势差、欧姆（Ω）表示电阻。你应当能够把任何导出单位用基本单位表示出来，例如 1 N = 1 kg m/s²，1 Pa = 1 N/m²。
| Prefix 词头 | Symbol 符号 | Factor 倍数 |
| giga 吉 | G | 10⁹ |
| mega 兆 | M | 10⁶ |
| kilo 千 | k | 10³ |
| centi 厘 | c | 10⁻² |
| milli 毫 | m | 10⁻³ |
| micro 微 | µ | 10⁻⁶ |
| nano 纳 | n | 10⁻⁹ |
direction, e.g. velocity, displacement, acceleration, force, weight). Scalars add numerically, while vectors must be added tip-to-tail; the resultant force on an object is the single vector that has the same effect as all the forces acting together. Density is a good example of a calculation that combines measurement skills with unit reasoning: ρ = m / V, measured in kg/m³ or g/cm³.
区分标量（只有大小，例如速率、路程、质量、能量、温度）和矢量（既有大小又有方向，例如速度、位移、加速度、力、重力）。标量直接数值相加，矢量必须首尾相接相加；物体所受的合力，就是与所有分力共同作用效果相同的那个单一矢量。密度是很好的一类计算题，它同时考查测量技能与单位推理：ρ = m / V，单位为 kg/m³ 或 g/cm³。
ρ = m ÷ V 1 g/cm³ = 1000 kg/m³
Finally, know how to improve the quality of measurements: use a ruler, vernier calipers or a micrometer for length, a top-pan balance for mass, and a measuring cylinder or displacement can for irregular volumes. Reduce random error by taking repeat readings and calculating a mean, and remember that precision (how small the scale divisions are) is not the same as accuracy (how close you are to the true value).
最后，要掌握提高测量质量的方法：长度用刻度尺、游标卡尺或千分尺，质量用电子天平，不规则体积用量筒或排水法。通过多次重复读数并取平均值可以减小随机误差，同时要记住：精密度（最小分度有多小）并不等于准确度（与真值的接近程度）。
2. Forces and Motion | 力与运动
This is the highest-yield topic in the whole paper. For distance-time graphs, the gradient gives speed and a horizontal line means the object is stationary; for velocity-time graphs, the gradient gives acceleration and the area under the line gives the distance travelled. Learn the four equations of uniformly accelerated motion and make sure you can pick the right one from the information given.
这是整份试卷中分值产出最高的话题。距离—时间图像中，斜率表示速率，水平直线表示物体静止；速度—时间图像中，斜率表示加速度，图线下的面积表示通过的路程。要牢记匀加速运动的四个公式，并能根据题目给出的已知量挑选正确的那个。
u) ÷ t v² = u² + 2as s = ut + ½at² s = (u + v)t ÷ 2
Newton' nd law gives F = ma, where F is the resultant force in newtons, m the mass in kilograms and a the acceleration in m/s². The third law says that if A exerts a force on B, then B exerts an equal and opposite force on A, acting on a different body. Weight is the force of gravity on a mass: W = mg, with g ≈ 9.8 N/kg near the Earth's surface.
牛顿定律是其余一切内容的基础。第一定律：若不受合力作用，物体保持静止或匀速直线运动。第二定律给出 F = ma，其中 F 是合力（牛顿），m 是质量（千克），a 是加速度（m/s²）。第三定律：若 A 对 B 施加一个力，则 B 对 A 施加一个大小相等、方向相反的力，且作用在不同物体上。重力是地球对质量的作用力：W = mg，地表附近 g ≈ 9.8 N/kg。
he diver accelerates; as speed increases, so does air resistance, until the two forces balance and the acceleration becomes zero. The diver then falls at constant terminal velocity. Momentum p = mv, and the impulse equation F × t = Δ(mv) explains why crumple zones and airbags reduce the force on the occupants by increasing the time taken to stop.
终端速度是考试中最爱考的问题之一。跳伞者刚跳出时，向下的重力大于向上的空气阻力，因而加速下落；随着速度增大，空气阻力也随之增大，直到两个力平衡、加速度为零，人就以恒定的终端速度下落。动量 p = mv，冲量公式 F × t = Δ(mv) 可以解释为什么溃缩区和安全气囊能通过延长停止时间来减小乘员所受的力。
3. Forces, Moments and Pressure | 力、力矩与压强
Hooke' s the spring constant in N/m. Be able to read a force-extension graph: the straight-line region obeys Hooke' first bends, and the area under the line gives the energy stored in the stretched spring.
胡克定律指出：只要不超过弹性限度，弹簧的伸长量与所加的力成正比，即 F = kx，其中 k 为劲度系数，单位 N/m。要会读力—伸长量图像：直线段服从胡克定律，正比极限是图线开始弯曲的位置，图线下的面积表示弹簧被拉伸时储存的能量。
icular distance from the pivot, measured in newton-metres (N m). An object is in equilibrium when the total clockwise moment equals the total anticlockwise moment, and you should be able to solve lever problems by taking moments about a chosen pivot. Everyday applications include spanners, crowbars, wheelbarrows and see-saws.
力的转动效果称为力矩：力矩 = 力 × 力臂（支点到力的垂直距离），单位是牛顿·米（N m）。当顺时针力矩总和等于逆时针力矩总和时，物体处于平衡状态；你应当能够通过选取合适的支点列力矩方程来解杠杆题。日常应用包括扳手、撬棍、独轮车和跷跷板。
moment = F × d p = F ÷ A p = hρg
ρg. This explains why dams are thicker at the bottom and why ear pain increases as you swim deeper. Upthrust is the upward force on an object in a fluid, equal to the weight of fluid displaced (Archimedes' principle); an object floats when its weight equals the upthrust acting on it.
压强是单位面积上的力，p = F/A，单位是帕斯卡。液体内部的压强取决于深度、密度和重力场强度：p = hρg。这解释了为什么水坝底部更厚，也解释了为什么潜得越深耳朵越疼。浮力是流体对物体向上的作用力，等于物体排开液体的重力（阿基米德原理）；当物体的重力等于所受浮力时，物体就漂浮。
4. Energy, Work and Power | 能量、功与功率
Energy cannot be created or destroyed, only transferred from one store to another; this is the principle of conservation of energy. You should be able to name the main stores (kinetic, gravitational potential, elastic potential, chemical, thermal/internal, nuclear, electrostatic, magnetic) and describe transfer pathways (mechanically, electrically, by heating, by radiation).
能量既不能创造也不能消灭，只能从一个能量库转移到另一个能量库，这就是能量守恒原理。你应当能够说出主要的能量库（动能、重力势能、弹性势能、化学能、热/内能、核能、静电势能、磁能），并描述转移途径（力学做功、电学做功、热传递、辐射）。
W = Fd P = W ÷ t = E ÷ t Eₖ = ½mv² Eₚ = mgh
P = W/t = E/t, measured in watts. Kinetic energy Eₖ = ½mv² and gravitational potential energy Eₚ = mgh are the two forms you will calculate most often, and many exam questions simply ask you to convert between them, for example a roller coaster at the top and bottom of a loop.
只要力使其作用点沿力的方向移动一段距离，就做了功：W = Fd，单位是焦耳。功率是能量转移的速率：P = W/t = E/t，单位是瓦特。动能 Eₖ = ½mv² 和重力势能 Eₚ = mgh 是你最常计算的两个形式，很多考题只是要求你在两者之间进行转换，例如过山车在环形轨道最高点和最低点的情况。
energy output with the total energy input: efficiency = useful output ÷ total input × 100% eating. A Sankey diagram is the standard way to show this, with the width of each arrow proportional to the energy it represents.
效率是比较有用能量输出与总能量输入的指标：效率 = 有用输出 ÷ 总输入 × 100%。在实践中，总有一部分能量因摩擦、空气阻力和电流热效应而耗散到周围环境的热能库中。桑基图是展示这一过程的标准方式，每条箭头宽度与该箭头代表的能量成正比。
5. Energy Transfer and Thermal Physics | 能量传递与热学
Heat is transferred by conduction, convection and radiation. Conduction happens mainly in solids, where vibrating particles pass energy along without the particles themselves travelling; metals are excellent conductors because of their free electrons acting as energy carriers. Convection happens in liquids and gases: a warmer region expands, becomes less dense and rises, while cooler, denser fluid sinks to replace it. Radiation is the transfer of energy by electromagnetic waves, needs no medium, and is most strongly emitted and absorbed by matt black surfaces.
热传递有三种方式：传导、对流和辐射。传导主要发生在固体中，振动着的粒子把能量依次传递而不发生粒子本身的迁移；金属是优良的导体，因为自由电子充当了能量载体。对流发生在液体和气体中：较热的区域膨胀、密度变小而上升，较冷、较密的流体下沉填补。辐射是以电磁波形式传递能量，不需要介质，且黑色无光泽表面对辐射的发射和吸收最强。
Q = mcΔT Q = mL
o change the state of 1 kg of a substance without changing its temperature: Q = mL. Learn the shape of a heating curve for ice turning into steam: two sloping sections (solid heating, liquid heating) and two flat sections (melting and boiling), where the energy supplied breaks bonds rather than raising temperature.
比热容是把 1 kg 某物质温度升高 1 °C 所需的能量：Q = mcΔT。比潜热是把 1 kg 某物质发生状态改变而温度不变所需的能量：Q = mL。要牢记冰变成水蒸气时的加热曲线形状：两段斜线（固体升温、液体升温）和两段水平段（熔化与沸腾），水平段所供给的能量用于破坏粒子间的结合，而不是升高温度。
Also revise gas pressure in terms of particle collisions with the container walls, and the relationship between the temperature of a gas and the average kinetic energy of its molecules. For the required practical on specific heat capacity, remember the key issues: use insulation to reduce thermal loss to the surroundings, stir the water to keep the temperature uniform, and use a low-voltage heater to reduce electrical heating of the connecting wires.
还要复习气体压强的微观解释——气体粒子与容器壁碰撞，以及气体温度与其分子平均动能之间的关系。对于比热容的必做实验，要记住几个关键问题：用保温材料减少向周围环境的热散失，搅拌水以保持温度均匀，使用低压加热器以减少连接导线的电热效应。
6. Waves: Properties, Light and Sound | 波：性质、光与声
A wave transfers energy without transferring matter. Know the definitions: amplitude is the maximum displacement from the rest position, wavelength is the distance between two successive identical points, frequency is the number of complete waves passing a point per second (measured in hertz, Hz), and period is the time for one complete wave. Transverse waves oscillate perpendicular to the direction of travel (light, water waves, all electromagnetic waves); longitudinal waves oscillate along the direction of travel (sound, ultrasound, P-waves).
波传递能量而不传递物质。要掌握定义：振幅是离开平衡位置的最大位移，波长是两个相邻同相点之间的距离，频率是每秒通过某点的完整波的个数（单位赫兹 Hz），周期是完成一次完整振动所需的时间。横波的振动方向与传播方向垂直（光、水波、所有电磁波）；纵波的振动方向与传播方向平行（声音、超声、P 波）。
v = f λ T = 1 ÷ f n = sin i ÷ sin r sin c = 1 ÷ n
dium; the refractive index n = sin i / sin r, and the wave bends towards the normal when it slows down. Total internal reflection happens when light travels from a denser to a less dense medium at an angle greater than the critical angle, given by sin c = 1/n. This is the principle behind optical fibres and prisms used in periscopes.
所有波都能发生反射、折射和衍射。对光而言，折射是因为光进入不同介质时速度发生了改变；折射率 n = sin i / sin r，光速减慢时光线向法线偏折。全反射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，临界角由 sin c = 1/n 给出。这正是光纤和潜望镜中棱镜的工作原理。
on of ultrasound to measure distance: distance = speed × time ÷ 2, remembering to halve the time for the round trip. The electromagnetic spectrum, from longest to shortest wavelength, is radio, microwave, infrared, visible, ultraviolet, X-ray and gamma; know one use and one hazard for each region.
声波是纵波，需要介质，在空气中速度约 340 m/s，不能在真空中传播。回声测距利用超声波的反射来测距：距离 = 速度 × 时间 ÷ 2，注意往返时间要除以 2。电磁波谱按波长由长到短依次为：无线电波、微波、红外线、可见光、紫外线、X 射线、γ 射线；要记住每个波段的一个用途和一个危害。
7. Electricity: Circuits and Components | 电学：电路与元件
erred per unit charge: V = W/Q. Resistance is defined by R = V/I and measured in ohms (Ω); for an ohmic conductor at constant temperature, current is directly proportional to potential difference, which is Ohm's law.
电流是电荷的流动速率：I = Q/t，其中 I 单位为安培，Q 为库仑，t 为秒。电势差是单位电荷所转移的能量：V = W/Q。电阻定义为 R = V/I，单位欧姆（Ω）；对温度恒定的欧姆导体，电流与电势差成正比，这就是欧姆定律。
p; V = W ÷ Q R = V ÷ I P = VI = I²R = V² ÷ R E = Pt
e voltage across each branch is the same and the current splits: 1/R = 1/R₁ + 1/R₂ + ... . Be able to describe how the resistance of a filament lamp changes as it heats up (non-ohmic, resistance increases), and how a thermistor's resistance falls as temperature rises while an LDR's resistance falls as light intensity increases.
串联电路中电流处处相同，电源电压由各元件分压：R = R₁ + R₂ + …。并联电路中各支路电压相同，电流发生分流：1/R = 1/R₁ + 1/R₂ + …。要能描述灯丝灯泡受热时电阻如何变化（非欧姆，电阻增大），以及热敏电阻的电阻随温度升高而减小、光敏电阻的电阻随光强增大而减小。
ften quoted in kilowatt-hours for domestic bills. For mains safety, know the role of the live, neutral and earth wires, why fuses and circuit breakers are fitted in the live wire, and how double insulation and earthing protect users from electric shock. Also revise the difference between direct current (d.c.) and alternating current (a.c.), and the frequency of UK mains (50 Hz, 230 V).
电功率 P = VI = I²R = V²/R，转移的电能为 E = Pt，家庭电费单上常用千瓦时（度）表示。关于市电安全，要掌握火线、零线和地线的作用，为什么保险丝和断路器要接在火线上，以及双重绝缘和接地如何保护使用者免遭电击。还要复习直流（d.c.）与交流（a.c.）的区别，以及英国市电的频率（50 Hz、230 V）。
8. Magnetism and Electromagnetism | 磁学与电磁感应
Magnetic materials include iron, steel, cobalt and nickel. Like poles repel, unlike poles attract, and magnetic field lines run from north to south outside a magnet. A current-carrying wire produces a magnetic field around it; wrapping the wire into a coil around a soft iron core produces an electromagnet, whose strength can be increased by increasing the current, increasing the number of turns, or using a soft iron core.
磁性材料包括铁、钢、钴和镍。同极相斥、异极相吸，磁体外部磁感线由 N 极指向 S 极。通电导线周围会产生磁场；把导线绕在软铁芯上就构成电磁铁，其磁性强弱可以通过增大电流、增加匝数或使用软铁芯来增强。
Two effects must be clearly separated in your answers. The motor effect is the force on a current-carrying conductor in a magnetic field, given by Fleming's left-hand rule; the size of the force increases with current, magnetic field strength and length of conductor in the field. The generator effect (electromagnetic induction) is the opposite: moving a conductor in a magnetic field, or changing the field around a conductor, induces a potential difference, and the induced current always opposes the change producing it (Lenz's law).
答题时必须清楚区分两个效应。电动机效应是磁场对通电导体的作用力，用弗莱明左手定则判断；力的大小随电流、磁场强度和导体在磁场中的长度增大而增大。发电机效应（电磁感应）则相反：让导体在磁场中运动，或改变导体周围的磁场，就会感应出电势差，且感应电流的方向总是阻碍引起它的变化（楞次定律）。
Vₚ ÷ Vₛ = Nₚ ÷ Nₛ (理想变压器)
. A step-up transformer has more turns on the secondary coil, a step-down transformer has fewer. Transformers only work with alternating current, and are close to 100% lly links the two coils. In the National Grid, transformers reduce energy loss in transmission cables by raising the voltage and so lowering the current for the same power.
变压器可以改变交流电源的电压：Vₚ/Vₛ = Nₚ/Nₛ。升压变压器副线圈匝数更多，降压变压器副线圈匝数更少。变压器只对交流电
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