📚 IGCSE WJEC Physics: Last-Minute Revision Notes | IGCSE WJEC 物理：考前冲刺笔记
These concise revision notes cover the key concepts, equations and common pitfalls across the WJEC IGCSE Physics specification. Use them to refresh your memory, check your understanding and build confidence before the exam. Every topic is presented in paired English and Chinese explanations, so you can study bilingually.
这本精炼的考前冲刺笔记涵盖了 WJEC IGCSE 物理大纲的核心概念、重要公式与常见易错点。无论是巩固记忆、查漏补缺还是建立信心，你都可以通过中英双语对照快速复习每个主题。
1. Motion and Kinematics | 运动学
Kinematics describes motion using displacement (vector), distance (scalar), speed (scalar), velocity (vector) and acceleration. Always assign a positive direction before using equations.
运动学用位移（矢量）、路程（标量）、速率（标量）、速度（矢量）和加速度描述运动。使用运动方程前务必规定正方向。
r objects falling freely, take acceleration due to gravity g = 10 m/s² (or 9.8) downwards.
三个匀加速直线运动方程仅适用于加速度恒定的情况。自由落体时取重力加速度 g = 10 m/s²（或 9.8），方向向下。
v = u + at | s = ut + ½at² | v² = u² + 2as
A common mistake is using s for distance travelled when acceleration is not constant; in a velocity–time graph, the area under the graph gives displacement, and the gradient gives acceleration.
常见错误是在加速度不恒定时使用上述公式。在速度–时间图中，图线下面积表示位移，斜率表示加速度。
2. Forces and Newton's Laws | 力与牛顿定律
ultant force acts upon it. Newton’s second law links force, mass and acceleration: F = ma.
牛顿第一定律指出，物体保持静止或匀速直线运动状态，除非受到合外力作用。第二定律将力、质量与加速度联系起来：F = ma。
mg. Do not confuse mass (kg) and weight (N). The centre of mass is the point where the weight of an object appears to act.
重力是由引力产生的力：W = mg。不要混淆质量（kg）和重力（N）。重心是物体重量似乎作用的点。
Newton’s third law pairs are equal in size, opposite in direction and act on two different bodies. Friction always opposes relative motion. Resultant force can be found by adding vector forces.
牛顿第三定律的作用力与反作用力大小相等、方向相反、作用在不同物体上。摩擦力总是阻碍相对运动。合力可通过矢量相加求得。
3. Energy, Work and Power | 能、功和功率
y is the capacity to do work; kinetic energy = ½mv², gravitational potential energy = mgh.
功 = 力 × 沿力方向移动的距离。能量是做功的能力；动能 = ½mv²，重力势能 = mgh。
tial, elastic potential, thermal, chemical, etc. Power is the rate of doing work: P = W/t.
在封闭系统中，总能量守恒。能量可在不同储存间转移：动能、重力势能、弹性势能、内能、化学能等。功率是做功的快慢：P = W/t。
Efficiency = (useful energy output / total energy input) × 100% , always check that the numbers are in the same unit and that you are using useful output.
效率 =（有用输出能量 / 总输入能量）× 100%。计算效率时务必确认单位一致，并使用有用的输出能量。
4. Waves: Nature and Properties | 波的性质
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.
波传递能量而不传递物质。横波（如光、水波）的振动方向与能量传递方向垂直；纵波（如声波）的振动方向与之平行。
1/f. Refraction occurs when a wave crosses a boundary and changes speed, causing a change in direction unless the wave hits the normal at 90°.
波速公式：v = fλ。周期 T = 1/f。当波穿过边界速度改变时发生折射，方向改变（除非垂直于界面入射）。
When drawing refraction diagrams, remember that the frequency remains constant; only wavelength and speed change. Total internal reflection can occur when light travels from a denser medium to a less dense one at an angle greater than the critical angle.
画折射图时切记频率不变，只有波长和速度改变。光从光密介质射向光疏介质且入射角大于临界角时，可以发生全内反射。
5. Electromagnetic Spectrum | 电磁波谱
rared, visible, ultraviolet, X-ray, gamma. All EM waves travel at 3 × 10⁸ m/s in a vacuum.
电磁波谱按频率递增、波长递减的顺序为：无线电波、微波、红外线、可见光、紫外线、X 射线、伽马射线。所有电磁波在真空中速度均为 3 × 10⁸ m/s。
Different regions have different uses: radio waves for communication, microwaves for cooking and satellite signals, infrared for thermal imaging, ultraviolet for sterilisation, X-rays for medical imaging, gamma rays for treating cancer.
不同波段用途各异：无线电波用于通信，微波用于烹饪和卫星信号，红外线用于热成像，紫外线用于杀菌，X 射线用于医学成像，伽马射线用于癌症治疗。
Hazards increase with frequency: UV causes skin damage, X-rays and gamma rays are ionising and can mutate DNA. Safety measures include using sun cream, lead shielding and limiting exposure time.
频率越高危害越大：紫外线导致皮肤损伤，X 射线和伽马射线具有电离能力可损伤 DNA。安全措施包括使用防晒霜、铅屏蔽和限制暴露时间。
6. Electricity Fundamentals | 电学基础
= energy transferred per unit charge: V = W/Q. Resistance R = V/I. Ohm’s law states that V ∝ I at constant temperature for an ohmic conductor.
电流 I 是电荷流动的速率：I = Q/t。电压（电势差）V = 单位电荷转移的能量：V = W/Q。电阻 R = V/I。欧姆定律指出，对于欧姆导体，温度恒定时 V ∝ I。
In series circuits, current is the same everywhere, total resistance is the sum of individual resistances, and the supply voltage is shared. In parallel circuits, voltage is the same across each branch, and total current is the sum of branch currents.
串联电路中电流处处相等，总电阻为各电阻之和，电源电压被分压。并联电路中各支路电压相等，总电流等于各支路电流之和。
ponent is ohmic or non-ohmic (e.g. filament lamp, diode) before applying Ohm’s law calculations.
常用公式有：P = IV，P = I²R，P = V²/R。在进行欧姆定律计算前，务必确认元件是否为欧姆导体（如灯丝、二极管为非线性元件）。
7. Mains Electricity and Safety | 家庭用电与安全
UK mains supply is 230 V, 50 Hz alternating current. The live wire (brown) carries the alternating potential difference, the neutral wire (blue) completes the circuit, and the earth wire (green/yellow) is a safety path to ground.
英国市电为 230 V、50 Hz 交流电。火线（棕色）携带交变电势差，零线（蓝色）构成回路，地线（绿/黄色）是安全接地路径。
A fuse is a thin wire that melts and breaks the circuit if current exceeds its rating; a circuit breaker does the same but can be reset. Double insulation eliminates the need for an earth wire in some appliances.
保险丝是细导线，电流超过额定值时熔断并断开电路；断路器功能相同但可复位。部分电器采用双层绝缘，因此无需地线。
sockets. Revise the calculations of power and energy: E = Pt (in kWh for domestic bills).
危害包括触电、过热和火灾。切勿湿手触摸开关，勿使插座过载。复习功率与电能计算：E = Pt（家庭电费账单以 kWh 计）。
8. Thermal Physics and Heat Transfer | 热物理与热传递
Heat is the transfer of thermal energy from a hotter object to a colder one. Conduction, convection and radiation are the three methods. Conduction is most effective in solids, especially metals due to free electrons.
热是热能由高温物体向低温物体的传递。三种方式为传导、对流和辐射。传导在固体中最为有效，金属因自由电子的存在而导热更快。
Convection occurs in fluids (liquids and gases) when warmer, less dense fluid rises and cooler, denser fluid sinks, setting up a convection current. Radiation can travel through a vacuum and is emitted by all objects above absolute zero.
对流发生在流体中，温度高、密度小的流体上升，温度低、密度大的流体下沉，形成对流循环。辐射可在真空中传播，任何高于绝对零度的物体都会发出热辐射。
ergy needed to change the state of 1 kg of a substance without temperature change: E = mL.
比热容 c 是使 1 kg 物质升高 1 °C 所需的能量：E = mcΔθ。潜热 L 是使 1 kg 物质在不改变温度的情况下发生物态变化所需的能量：E = mL。
9. Atomic Structure and Radioactivity | 原子结构与放射性
Atoms have a tiny, positively charged nucleus containing protons and neutrons, surrounded by electrons in shells. Atomic number Z is the number of protons; mass number A is protons + neutrons.
原子有一个极小的带正电的原子核，由质子和中子组成，核外电子分层排布。原子序数 Z 是质子数；质量数 A 是质子数 + 中子数。
Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. Some isotopes are unstable and emit ionising radiation: alpha (α), beta (β) or gamma (γ).
同位素是质子数相同而中子数不同的同种元素原子。某些同位素不稳定，会发出电离辐射：α、β 或 γ 射线。
Alpha is a helium nucleus (highly ionising, stopped by paper); beta is a fast electron (moderately ionising, stopped by aluminium); gamma is electromagnetic (low ionising, reduced by thick lead). Radioactive decay is random; half-life is the time taken for half the nuclei in a sample to decay.
α 粒子是氦核（电离能力最强，纸即可阻挡）；β 粒子是高速电子（电离能力中等，铝片可阻挡）；γ 是电磁波（电离能力弱，需厚铅板减弱）。衰变是随机的；半衰期是样品中一半原子核发生衰变所需的时间。
10. Nuclear Fission and Fusion | 核裂变与核聚变
Nuclear fission is the splitting of a large, unstable nucleus (e.g. uranium-235) after absorbing a neutron, releasing energy and more neutrons. These neutrons can trigger a chain reaction.
核裂变是重的不稳定核（如铀-235）吸收一个中子后分裂成两个较小的核，同时释放能量和更多中子。这些中子可引发链式反应。
In a nuclear reactor, control rods absorb neutrons to control the rate of fission. The heat released is used to produce steam that drives a turbine and generator. Nuclear fusion combines light nuclei (e.g. hydrogen) to form a heavier nucleus, releasing enormous energy – this is the process that powers stars.
在核反应堆中，控制棒吸收中子以控制裂变速率。释放的热量用于产生蒸汽驱动汽轮机和发电机。核聚变是轻核（如氢）结合成较重核，释放巨大能量，这是恒星的能量来源。
tained net energy output. Both processes involve tiny mass losses, converted to energy according to E = mc².
聚变需要极高的温度和压力以克服静电排斥力。目前的聚变反应堆尚无法持续产生净能量输出。两种过程均涉及微小质量亏损，按照 E = mc² 转化为能量。
11. Space Physics | 空间物理
The Solar System consists of the Sun, planets, moons, asteroids and comets. Planets orbit the Sun in elliptical paths; moons orbit planets. Gravitational force provides the centripetal force for these orbits.
太阳系由太阳、行星、卫星、小行星和彗星组成。行星沿椭圆轨道绕太阳运行，卫星绕行星运行。引力为这些轨道运动提供向心力。
For a stable orbit, the gravitational pull of the larger body must balance the required centripetal force. Orbital speed changes with distance: the closer the object to the star, the faster it orbits.
稳定轨道要求大质量物体的引力与所需的向心力平衡。轨道速度随距离变化：离恒星越近，轨道速度越快。
Stars evolve from nebulae. A star like the Sun becomes a red giant then a white dwarf; more massive stars become red supergiants, then undergo a supernova, leaving behind a neutron star or a black hole. The Big Bang theory explains the origin of the Universe; evidence includes cosmic microwave background radiation and galactic red-shift.
恒星从星云演化而来。类似太阳的恒星变成红巨星，再成为白矮星；质量更大的恒星变为红超巨星，经过超新星爆发后留下中子星或黑洞。大爆炸理论解释宇宙起源，证据包括宇宙微波背景辐射和星系红移。
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