📚 IGCSE Edexcel Physics Unit Test Mastery | IGCSE Edexcel 物理单元测试攻克指南
Unit tests in IGCSE Edexcel Physics are your stepping stones to exam success. They check not just your recall of facts, but your ability to apply concepts, handle equations, and interpret data. This guide walks you through the core topics, typical question styles, and smart revision strategies so you can walk into any unit test feeling prepared and confident.
IGCSE Edexcel 物理的单元测试是通向大考成功的基石。它不仅考查你对知识的记忆，更检验你运用概念、处理方程和解读数据的能力。本指南将带你梳理核心主题、典型题型和高效复习策略，让你在任何一次单元测试中都能胸有成竹。
1. Forces and Motion Foundations | 力与运动基础
You must be able to interpret distance-time and velocity-time graphs, calculating speed, acceleration, and distance from gradients and areas. Recognising the shapes for constant velocity, acceleration, and deceleration is essential.
你必须能够解读距离-时间图和速度-时间图，并能根据斜率和面积计算速率、加速度和距离。识别匀速、加速和减速对应的图形形状至关重要。
Newton' ion has an equal and opposite reaction. Examples include seat belts and rocket propulsion.
牛顿三大定律是几乎所有力学问题的基础。牢记合力等于质量乘以加速度（F = ma），并且作用力与反作用力大小相等、方向相反。安全带和火箭推进是常见例子。
locities after an event, so practise using the formula p = mv and conservation statements.
碰撞和爆炸中动量守恒（总动量前 = 总动量后）。你可能需要计算事件后的速度，因此要练习使用公式 p = mv 和守恒表述。
ockwise moments) must be applied, with moment = force × perpendicular distance from pivot.
力矩与平衡常出现在涉及跷跷板或杠杆的单元测试中。力矩原理（顺时针力矩之和 = 逆时针力矩之和）必须应用，力矩 = 力 × 到支点的垂直距离。
| Quantity | Formula | Unit |
|---|---|---|
| Acceleration | a = (v - u)/t | m/s² |
| Final velocity² | v² = u² + 2as | (m/s)² |
| Displacement | s = ut + ½at² | m |
| Force | F = ma | N |
| Momentum | p = mv | kg m/s |
2. Electricity Circuits and Components | 电路与元件
You need to recall standard circuit symbols and be able to draw and interpret series and parallel circuits. In a series circuit, current is the same everywhere; in parallel, potential difference is the same across branches.
你需要记住标准电路符号，并能够绘制和解读串联与并联电路。在串联电路中，各处电流相等；在并联电路中，各支路两端电压相等。
Ohm's law (V = IR) is central. A resistor obeys Ohm' perature. I-V graphs for a fixed resistor, filament lamp, and diode are common test items.
欧姆定律（V = IR）是核心。若某一电阻器在恒温下电阻恒定，则它遵循欧姆定律。定值电阻、白炽灯和二极管的 I-V 特性图是常见考题。
onship between resistance and power (P = I²R or P = V²/R) often appears in rearrangements.
电功率和电能的运算用到 P = IV 与 E = IVt。要准备好将时间换算为秒，并掌握千瓦时。电阻与功率的关系（P = I²R 或 P = V²/R）常在公式变换中出现。
Domestic electricity questions test your understanding of the live, neutral, and earth wires, fuses, and double insulation. Safety features and the ring main circuit are key.
家庭用电题目考察你对火线、零线、地线、保险丝和双重绝缘的理解。安全特性和环形干线电路是关键。
- Series: Rtotal = R₁ + R₂ + ...
- Parallel: 1/Rtotal = 1/R₁ + 1/R₂ + ...
3. Waves: Light and Sound | 波：光与声
Transverse waves (e.g., light, ripples) vibrate perpendicular to energy travel; longitudinal waves (e.g., sound) vibrate parallel. You must label amplitude, wavelength, crest, trough, compression, and rarefaction.
横波（如光波、水波）振动方向与能量传播方向垂直；纵波（如声波）振动方向平行。你必须会标出振幅、波长、波峰、波谷、疏部和密部。
y. Pay attention to units: speed m/s, frequency Hz, wavelength m. Questions often provide a diagram of a waveform and ask you to calculate one quantity from the other two.
波动方程 v = fλ 应用广泛。注意单位：波速 m/s，频率 Hz，波长 m。题目常给出波形图，要求你从已知的两个量计算第三个量。
lection appear with ray diagrams. Know the law of reflection (angle i = angle r) and Snell' water, glass, and fibre optics. The critical angle concept is tested with core practicals.
反射、折射和全内反射会出现光路图。熟知反射定律（入射角 = 反射角）和斯涅尔定律，尤其是水、玻璃和光纤中的情况。临界角概念结合核心实验进行考查。
Sound waves require a medium and can be reflected as echoes. Ultrasound and its uses (sonar, medical scanning) are examined, along with the frequency range of human hearing (20 Hz – 20 kHz).
声波需要介质传播，且能反射形成回声。超声波及其应用（声呐、医学扫描）以及人耳听觉频率范围（20 Hz – 20 kHz）均在考查之列。
4. Energy Resources and Energy Transfer | 能源与能量转移
You should classify energy stores (kinetic, gravitational potential, thermal, chemical, etc.) and describe transfers in systems such as a pendulum or roller coaster. Sankey diagrams visualise energy efficiency.
你应对能量储存进行分类（动能、重力势能、热能、化学能等），并描述钟摆或过山车等系统中的能量转移。桑基图用于可视化能量效率。
transfer: P = E/t or P = W/t. Be comfortable converting between joules and kilowatt-hours.
做功 = 力 × 沿力的方向移动的距离。功率是能量转移的速率：P = E/t 或 P = W/t。要能熟练地在焦耳和千瓦时之间转换。
Renewable and non-renewable resources are compared. Wind, solar, tidal, hydroelectric, and biomass are renewable; fossil fuels and nuclear fuel are not. Evaluate the advantages and disadvantages, including environmental impact.
可再生与不可再生能源需作比较。风能、太阳能、潮汐能、水力和生物质为可再生能源；化石燃料与核燃料为不可再生能源。评估其优缺点，包括环境影响。
Thermal energy transfer by conduction, convection, and radiation appears in both daily life and exam scenarios. Conduction is important in solids; convection in fluids; radiation does not require a medium.
热能的传导、对流和辐射传递既出现在生活中也出现在考题里。传导在固体中重要；对流在流体中；辐射无需介质。
5. Solids, Liquids and Gases | 固体、液体与气体
on. You may need to find the volume of irregular objects by displacement and then compute density. Explain why some substances float or sink based on density.
密度 ρ = m/V 是常规计算。你可能需要通过排水法测量不规则物体的体积，再计算密度。根据密度解释为何某些物体会浮起或下沉。
s with depth and density. The barometer and manometer probe atmospheric and gas pressures.
固体压强 p = F/A 与力矩和液压紧密联系。液体压强 p = hρg 随深度和密度增加。气压计和压强计用于测量大气压和气体压强。
The behaviour of gas molecules is explained by the kinetic particle model. Boyle' at constant temperature. Be ready to calculate final pressure or volume using p₁V₁ = p₂V₂.
气体分子的行为用粒子动力模型解释。波义耳定律指出，对于恒定温度下的一定质量气体，pV 为常数。准备好用 p₁V₁ = p₂V₂ 计算末态压强或体积。
Changes of state (melting, boiling, condensation, freezing) are accompanied by energy changes but no temperature change until the state change is complete. Latent heat concepts may be tested in unit papers.
物态变化（熔化、沸腾、液化、凝固）伴随着能量变化，但在状态变化完成前温度保持不变。潜热概念可能在单元试卷中涉及。
6. Magnetism and Electromagnetism | 磁学与电磁学
Permanent magnets have N and S poles; field lines point from north to south. Electromagnets are temporary magnets whose strength can be changed by current, number of coils, or core material.
永磁体具有 N 极和 S 极；磁感线从北极指向南极。电磁铁是临时磁体，其强弱可通过改变电流、线圈匝数或铁芯材料来调节。
The motor effect (Fleming' he force is maximum when the wire is perpendicular to the field. Calculations use F = BIL.
电动机效应（弗莱明左手定则）预测通电导线在磁场中受力的方向。当导线与磁场垂直时受力最大。计算使用 F = BIL。
Electromagnetic induction occurs when a conductor cuts magnetic field lines, generating an e.m.f. Generators and dynamos convert mechanical energy into electrical energy. Lenz's law explains the direction of induced current.
当导体切割磁感线时发生电磁感应，产生电动势。发电机和直流发电机将机械能转化为电能。楞次定律解释了感应电流的方向。
transformers) is a favourite calculation. Step-up and step-down applications are examined.
变压器通过绕在铁芯上的两组线圈改变交流电压。匝数比方程 Vₚ/Vₛ = nₚ/nₛ（理想变压器）是经典计算题。升压与降压的应用均会考查。
7. Radioactivity and Particles | 放射性与粒子
The nuclear atom has a tiny positive nucleus surrounded by electrons in shells. Atomic number Z and mass number A define isotopes. Alpha scattering experiment proved the nuclear model.
核式原子有一个微小的带正电的原子核，核外电子分层排布。原子序数 Z 和质量数 A 定义了同位素。α 粒子散射实验证明了核式模型。
Alpha, beta, and gamma radiation have different ionising power, penetration, and behaviour in electric and magnetic fields. Must recall their nature: helium nucleus, electron, electromagnetic wave.
α、β 和 γ 辐射具有不同的电离能力、穿透能力以及在电场和磁场中的表现。必须记住它们的本质：氦核、电子、电磁波。
Nuclear equations show changes in atomic and mass numbers during decay. Alpha decay reduces Z by 2 and A by 4; beta decay increases Z by 1 with no change in A. Gamma emission has no effect on A or Z.
核方程显示衰变过程中原子序数和质量数的变化。α 衰变 Z 减 2、A 减 4；β 衰变 Z 加 1、A 不变；γ 辐射不改变 A 和 Z。
Half-life is the time for half the nuclei in a sample to decay. You will interpret decay curves or tables of counts per minute. Applications include carbon dating and medical tracers. Background radiation must be subtracted.
半衰期是样本中一半原子核发生衰变所需的时间。你将解读衰变曲线或每分钟计数表。应用包括碳年代测定和医用示踪剂。必须扣除本底辐射。
8. Astrophysics (Optional Topic) | 天体物理（选修主题）
ipetal force for circular orbits. Orbital speed, radius, and period are linked: v = 2πr/T.
太阳系包括绕太阳运行的行星、卫星、彗星和小行星。引力为圆形轨道提供向心力。轨道速率、半径和周期相关：v = 2πr/T。
Stars form from nebulae, undergo a main sequence lifetime, and then follow different paths depending on mass. A low-mass star becomes a white dwarf; a high-mass star may go supernova and leave a neutron star or black hole.
恒星由星云形成，经历主序星阶段，随后根据质量沿不同路径演化。低质量恒星变为白矮星；大质量恒星可能发生超新星爆发，留下中子星或黑洞。
The redshift in light from distant galaxies shows that the Universe is expanding. The greater the redshift, the faster the galaxy moves away. This supports the Big Bang theory. Cosmic microwave background radiation is another piece of evidence.
来自遥远星系的光发生红移，表明宇宙在膨胀。红移越大，星系退行速度越快。这支持了大爆炸理论。宇宙微波背景辐射是另一项证据。
9. Calculation and Rearrangement Skills | 计算与公式变形技巧
Every physics unit test includes numerical problems. Always list the known quantities with their units before picking an equation. Use the triangle method or algebraic rearrangement to solve for the unknown.
每一次物理单元测试都包含数值问题。选择公式前，始终先列出已知量及其单位。使用三角形法或代数变形来求解未知量。
its like mm² to m² (divide by 1 000 000), cm³ to m³ (×10⁻⁶), and hours to seconds (×3600).
密切注意有效数字：你的答案应与给定数据中最低精度的数字匹配。练习单位换算，如 mm² 换算为 m²（除以 1 000 000），cm³ 换算为 m³（乘以 10⁻⁶），以及小时换算为秒（乘以 3600）。
velocity in kinetic energy (KE = ½mv²). Double-check your substitution before calculating.
常见陷阱包括使用错误的质量单位（克代替千克），以及在计算动能（KE = ½mv²）时忘记对速度平方。在计算前务必再次检查代入数值。
For proportional reasoning questions, set up a proportion rather than calculating from scratch. This saves time and reduces arithmetic mistakes.
对于比例推理题，可建立比例关系而无需从头计算。这能节省时间并减少算术错误。
10. Experimental Skills and Data Analysis | 实验技能与数据分析
You are expected to describe how to measure quantities using a ruler, micrometer, stopwatch, ammeter, voltmeter, thermometer, and measuring cylinder. Know the typical precision of each instrument.
你应能描述如何用直尺、千分尺、秒表、电流表、电压表、温度计和量筒测量物理量。了解每种仪器的典型精确度。
When plotting graphs, use more than half the grid, label axes with quantity and unit, draw a line of best fit, and do not force it through the origin unless justified. You may need to calculate gradient or intercept.
绘图时，图线应占据超过一半的方格，如实标注轴名与单位，画出最佳拟合线，非必要时勿强行使直线过原点。你可能需要计算斜率或截距。
Handling anomalous results means identifying values that do not fit the pattern, repeating readings, and averaging. Always refer to the potential source of error and how it affects the result.
处理异常数据意味着识别出不符合规律的值，进行重复读数并取平均值。始终指出可能的误差来源及其对结果的影响。
In core practical common questions, such as investigating the resistance of a wire or measuring the speed of sound, you should be able to state the independent, dependent, and control variables clearly.
在核心实验常见问题中，比如探究导线电阻或测量声速，你应能清晰陈述自变量、因变量和控制变量。
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