📚 High-Frequency Summary for IGCSE WJEC Physics | IGCSE WJEC 物理：高频考点总结
This revision guide highlights the most frequently examined topics in IGCSE WJEC Physics. Each section pairs key concepts in English and Chinese, helping you consolidate understanding quickly and effectively. Focus on clear definitions, formula applications, and typical graph analyses that appear repeatedly in past papers.
本复习指南提炼了 IGCSE WJEC 物理中最常考查的专题。每个要点均以中英双语对照呈现，帮助你快速巩固核心概念。请重点关注定义表述、公式应用以及历年真题中反复出现的图像分析。
1. Scalars, Vectors and Motion Graphs | 标量、矢量与运动图像
Speed is a scalar quantity that only has magnitude, while velocity is a vector quantity with both magnitude and direction. In a distance-time graph, the gradient represents speed; in a displacement-time graph, the gradient gives velocity. A straight line indicates constant speed or velocity, and a curved line shows acceleration or deceleration.
速率是只有大小的标量，而速度是既有大小又有方向的矢量。在距离-时间图像中，斜率代表速率；在位移-时间图像中，斜率表示速度。直线表示匀速，曲线则表明存在加速或减速。
The area under a speed-time graph equals the distance travelled. For a velocity-time graph, the area represents displacement, and the gradient equals acceleration. Typical exam questions ask you to calculate acceleration using a = (v – u) / t and to determine total distance from the shape of the graph.
速度-时间图下方的面积等于通过的距离。在速率-时间图中，面积代表位移，斜率代表加速度。常见的考题要求你利用 a = (v – u) / t 计算加速度，并根据图像形状求出总移动距离。
2. Newton’s Laws and Balanced Forces | 牛顿定律与力的平衡
Newton’s first law states that an object remains at rest or in uniform motion unless acted upon by a resultant force. Newton’s second law, F = ma, directly links resultant force, mass and acceleration. The third law reminds us that forces always occur in action-reaction pairs on different bodies.
牛顿第一定律指出，除非受到合力作用，物体将保持静止或匀速直线运动。牛顿第二定律 F = ma 直接建立了合力、质量与加速度的关系。第三定律则强调力总是成对出现，作用在不同的物体上。
When forces on an object are balanced, the resultant force is zero and the object moves with constant velocity or stays stationary. Common examples include a skydiver reaching terminal velocity when air resistance equals weight, and a car cruising at a steady speed when driving force matches friction and air resistance.
当物体受到的力达到平衡时，合力为零，物体保持匀速运动或静止。常见例子有：跳伞者达到终极速度时空气阻力等于重力，以及汽车匀速行驶时驱动力与摩擦及空气阻力平衡。
3. Work, Energy and Power | 功、能量与功率
Work done is calculated by W = F × d, where the force must be in the direction of motion. Energy is always conserved: it can be transferred or transformed but never destroyed. Kinetic energy is given by Ek = ½ m v² and gravitational potential energy by Ep = m g h.
功的计算公式为 W = F × d，其中力必须沿着运动方向。能量总是守恒的：可以转移或转化，但不会凭空消失。动能由 Ek = ½ m v² 给出，重力势能则由 Ep = m g h 给出。
Power is the rate of work done or energy transferred: P = W / t or P = ΔE / t. Examiners frequently test conversion between potential and kinetic energy in pendulum and roller-coaster problems, where you ignore air resistance and equate mgh to ½mv².
功率是做功或能量转移的速率：P = W / t 或 P = ΔE / t。考官常考查摆锤和过山车问题中势能与动能的转化，通常忽略空气阻力，直接令 mgh = ½mv² 进行求解。
4. Density and Pressure in Fluids | 密度与流体压强
Density is mass per unit volume, ρ = m / V. The pressure on a surface is P = F / A. In liquids, pressure increases with depth and density, following P = h ρ g. This explains why dams are thicker at the base.
密度是单位体积的质量，ρ = m / V。固体表面压强为 P = F / A。液体内部压强随深度和密度增加而增大，公式为 P = h ρ g，这就是大坝底部更厚的原因。
Atmospheric pressure can be measured with a mercury barometer or an aneroid barometer. As altitude increases, atmospheric pressure decreases because the column of air above is shorter and less dense. Manometers show pressure differences using a liquid column and are frequently featured in practical-based questions.
大气压可用水银气压计或空盒气压计测量。海拔升高时大气压下降，因为上方空气柱变短且密度变小。U形管压力计通过液柱高度差显示压强差，常见于实验类考题。
5. General Wave Properties | 波的一般特性
The wave equation v = f λ links speed, frequency and wavelength. Frequency is the number of complete waves per second, measured in hertz (Hz). Period T = 1/f is the time for one full cycle. All waves transfer energy without transferring matter.
波动方程 v = f λ 将波速、频率和波长联系起来。频率是每秒完整波的个数，单位赫兹（Hz）。周期 T = 1/f 是一个完整循环所需的时间。所有波传递能量而不传递物质。
- Transverse waves: oscillations are perpendicular to energy travel. Examples – light, water ripples, electromagnetic waves. | 横波：振动方向垂直于能量传播方向。例：光波、水波、电磁波。
- Longitudinal waves: oscillations are parallel to energy travel. Example – sound waves. They consist of compressions and rarefactions. | 纵波：振动方向平行于能量传播方向。例：声波，由疏部和密部组成。
Reflection, refraction and diffraction are key wave behaviours. Refraction occurs when a wave changes speed at a boundary, altering wavelength and direction unless it enters along the normal. Diffraction is noticeable when the gap size is similar to the wavelength.
反射、折射和衍射是波的关键行为。折射发生在波从一种介质进入另一种介质速度改变时，除非入射方向垂直于界面，否则波长和方向都会改变。当缝隙大小接近波长时，衍射现象明显。
6. Electromagnetic Spectrum | 电磁波谱
The electromagnetic spectrum is arranged by frequency and wavelength: radio, microwave, infrared, visible, ultraviolet, X-ray, gamma. All travel at the speed of light in a vacuum, c = 3.0 × 10⁸ m/s. Higher frequency means higher energy and shorter wavelength.
电磁波谱按频率和波长排列：无线电波、微波、红外线、可见光、紫外线、X射线、伽马射线。它们在真空中均以光速 c = 3.0 × 10⁸ m/s 传播。频率越高，能量越大，波长越短。
Each region has distinct uses and dangers. Microwaves heat food and are used in communications, while infrared is used in thermal imaging and remote controls. Ultraviolet can cause skin cancer, X-rays see inside the body but can damage cells, and gamma rays are used to treat cancer but are highly ionising.
各波段都有独特的用途和危害。微波用于加热食物和通信，红外线用于热成像和遥控器。紫外线可能诱发皮肤癌，X射线可用于透视但会损伤细胞，伽马射线用于治疗癌症但电离作用很强。
7. Electric Charge, Current and Voltage | 电荷、电流与电压
Electric current is the rate of flow of charge: I = Q / t. In a metal, current is carried by free electrons moving from negative to positive, while conventional current flows from positive to negative. The unit of charge is the coulomb (C).
电流是电荷流动的速率：I = Q / t。在金属中，电流由自由电子从负极移向正极携带，而传统电流方向则规定为正电荷移动的方向。电荷的单位是库仑（C）。
Voltage (potential difference) is the energy transferred per unit charge: V = W / Q. Electromotive force (e.m.f.) is the total energy supplied by a cell or battery per unit charge. In a series circuit, current is the same everywhere and voltages add up; in a parallel circuit, current splits while voltage is the same across each branch.
电压（电势差）是单位电荷转移的能量：V = W / Q。电动势（e.m.f.）是电源给予单位电荷的总能量。串联电路中电流处处相等，总电压等于各元件电压之和；并联电路中电流分流，各支路两端电压相等。
8. Resistance and I-V Characteristics | 电阻与 I-V 特性
Resistance measures how difficult it is for current to flow: R = V / I. Ohm’s law states that, at constant temperature, current is directly proportional to voltage for a metallic conductor, giving a straight-line I-V graph through the origin.
电阻衡量电流通过的难易程度：R = V / I。欧姆定律指出，在温度不变的条件下，金属导体的电流与电压成正比，其 I-V 图像是一条通过原点的直线。
| Component | I-V characteristic | 中文说明 |
|---|---|---|
| Fixed resistor | Straight line through origin | 定值电阻，过原点直线 |
| Filament lamp | Curve flattening at high V (resistance increases with temperature) | 灯丝灯泡，高温时电阻增大，曲线趋平 |
| Diode | Conducts only in forward bias above threshold voltage | 二极管，仅在正向偏压超过阈值时导通 |
Factors affecting resistance include length (longer → higher R), cross-sectional area (larger area → lower R), material and temperature. A thermistor’s resistance drops as temperature rises; an LDR’s resistance falls in bright light. These are frequently used in sensor circuits.
影响电阻的因素有长度（越长电阻越大）、横截面积（面积越大电阻越小）、材料和温度。热敏电阻随温度升高阻值降低；光敏电阻在强光下阻值下降，常用于传感器电路。
9. Magnetism and Electromagnetism | 磁学与电磁学
Permanent magnets have a north and south pole; like poles repel, unlike poles attract. A magnetic field line shows the direction a north pole would move. The field is strongest where lines are closest, near the poles.
永磁体有北极和南极，同名磁极相互排斥，异名磁极相互吸引。磁感线表示北极受力的方向，磁感线越密集的地方磁场越强，即磁极附近。
An electromagnet is created by passing current through a coil of wire (solenoid), often wrapped around a soft iron core to strengthen the field. The motor effect occurs when a current-carrying wire experiences a force in a magnetic field. Fleming’s left-hand rule predicts the direction of thrust: First finger = Field, second finger = Current, thumb = Motion.
电磁铁由通电螺线管产生磁场，常加入软铁芯以增强磁场。电动机效应是指通电导线在磁场中受到力的作用。弗莱明左手定则可以帮助判断受力方向：食指 = 磁场，中指 = 电流，拇指 = 运动。
Electromagnetic induction occurs when a conductor cuts magnetic field lines, generating a voltage. This principle is used in generators and dynamos. In a coil, the induced voltage increases if the magnet is moved faster, the coil has more turns, or the magnet is stronger.
电磁感应是指导体切割磁感线时产生电压，发电机和直流发电机都基于这一原理。在线圈中，磁铁移动越快、线圈匝数越多或磁铁越强，产生的感应电压就越大。
10. Radioactivity and Half-Life | 放射性与半衰期
An atom consists of a nucleus of protons and neutrons, surrounded by electrons. Radioactive decay occurs when an unstable nucleus emits radiation. The three types are alpha (α), beta (β) and gamma (γ). Alpha particles are helium nuclei, beta particles are fast electrons, and gamma rays are electromagnetic waves.
原子由质子和中子组成的原子核以及绕核电子构成。当不稳定的原子核发射射线时发生放射性衰变。辐射分为三种：α（氦核），β（高速电子）和γ（电磁波）。
| Radiation | Penetration | Ionising power | Stopped by |
|---|---|---|---|
| Alpha | Low | Very high | Paper, skin |
| Beta | Medium | Moderate | Aluminium sheet |
| Gamma | High | Low | Thick lead, concrete |
Half-life is the time taken for half of the unstable nuclei in a sample to decay, or for the count rate to fall to half its original value. It is a constant for a given isotope and is unaffected by temperature or pressure. Radioactivity has uses in smoke detectors (alpha), thickness monitoring (beta) and cancer treatment (gamma).
半衰期是指样品中半数不稳定的原子核发生衰变，或计数率降至初始值一半所需的时间。对于特定同位素，半衰期是常数，不受温度或压强影响。放射性的应用包括烟雾探测器（α）、厚度监控（β）和癌症放疗（γ）。
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Cancel reply