📚 WJEC Year 13 Physics: A Quick-Memorisation Guide to Key Terminology | WJEC 十三年级物理：关键术语速记指南
Mastering physics at Year 13 requires more than just solving equations; it demands a deep, intuitive grasp of the exact terminology defined by the WJEC specification. This guide breaks down the most important terms topic by topic, pairing clear English definitions with Chinese explanations and memory hooks. Use it as a checklist, a quick reference, and a confidence builder before your exams.
在十三年级物理中取得高分，远不止会解题那么简单；你必须对 WJEC 考试大纲中精确定义的术语有深刻、直观的理解。本指南按主题逐一拆解最重要的术语，将清晰的英文定义与中文解释和记忆窍门配对。可将其用作核查清单、速查手册和考前信心增强剂。
1. Mechanics and Motion | 力学与运动
Displacement – a vector quantity representing the change in position of an object; it is the straight-line distance from the initial to the final point, taken in a particular direction. Never confuse displacement with distance, which is scalar and measures the total path length. Memory tip: 'Displacement' starts with 'D' like 'Direction'.
位移 – 表示物体位置变化的矢量；它是从起点到终点的直线距离，并带有特定方向。切勿将位移与标量路程混淆，路程测量的是总路径长度。记忆窍门：“位”即位置变化，“移”有移动方向。
Velocity – the rate of change of displacement with respect to time, also a vector. The magnitude of velocity is speed, but adding a direction turns speed into velocity. Thinking of 'v' as a vector velocity and 's' as scalar speed can help.
速度 – 位移对时间的变化率，同样是矢量。速度的大小是速率，但加上方向后速率就变成了速度。联想记忆：'v' 代表有方向的矢量速度，而 's' 代表只有大小的标量速率。
Acceleration – the rate of change of velocity. An object accelerates whenever its speed changes or its direction changes. In uniform circular motion there is acceleration even when speed is constant. Remember: 'accelerate' means any velocity change, not just 'speeding up'.
加速度 – 速度的变化率。只要物体的速率或方向发生变化，物体就在加速。在匀速圆周运动中，即使速率恒定也存在加速度。记住：“加速”指任何速度变化，而不仅仅是“加快”。
Momentum – the product of an object' um is a vector quantity and is conserved in isolated systems, provided no external resultant force acts. The phrase 'momentum is mass in motion' helps to lock in the concept.
动量 – 物体的质量与速度的乘积，p = m v。动量是矢量，并且在孤立系统中若不受外合力作用则守恒。用“动量就是运动中的质量”这句话来固化概念。
Impulse – the change in momentum of an object, equal to the average resultant force multiplied by the time for which it acts (FΔt). Graphically, the impulse is the area under a force–time graph. Link: 'Impulse Invests momentum'.
冲量 – 物体动量的变化量，等于平均合力乘以力作用的时间 (FΔt)。在图像上，冲量是力—时间图下的面积。联想：“冲量投入动量”。
2. Circular Motion and Gravitational Fields | 圆周运动与引力场
Angular velocity (ω) – measured in rad s⁻¹. It relates linear speed v to radius r through v = ω r. Think of ω as 'how many radians are swept out per second'.
角速度 (ω) – 角位移的变化率，单位为 rad s⁻¹。它通过 v = ω r 将线速度与半径联系起来。想象 ω 是“每秒扫过多少弧度”。
Centripetal force – the resultant force directed toward the centre of a circular path that keeps an object moving in that circle. It does no work because it acts perpendicularly to the velocity. 'Centripetal' means 'centre-seeking'. Do not confuse it with the fictitious 'centrifugal' force.
向心力 – 指向圆心的合力，使物体保持圆周运动。因始终与速度垂直，向心力不做功。“向心”即“指向中心”。切勿与虚构的“离心力”混淆。
Gravitational field strength (g) – e per unit mass experienced by a small test mass placed in a gravitational field. On Earth's surface g ≈ 9.81 N kg⁻¹. The formula g = GM/r² shows it follows an inverse-square law.
引力场强 (g) – 单位质量在引力场中受到的力。地球表面 g ≈ 9.81 N kg⁻¹。公式 g = GM/r² 表明引力场强遵循平方反比律。
Gravitational potential (V) – the work done per unit mass in bringing a test mass from infinity to a point in a field. It is always negative for an attractive field, with zero at infinity. Remember: 'Potential is the work of moving mass in from infinity'.
引力势 (V) – 将单位质量从无穷远移至场中某点所做的功。在吸引场中引力势总为负值，无穷远处为零。记忆：“引力势是从无穷远处搬来质量所做的功”。
Kepler's third law – the square of the orbital period T is proportional to the cube of the average orbital radius r (T² ∝ r³). This law emerges directly from equating gravitational force to centripetal requirement. Think 'T² relates to r³ for all planets orbiting the same star'.
开普勒第三定律 – 轨道周期 T 的平方与平均轨道半径 r 的立方成正比 (T² ∝ r³)。该定律可直接由引力等于所需的向心力推导出来。记作“对于绕同一恒星运行的所有行星，T² 与 r³ 关联”。
3. Thermal Physics | 热物理学
Internal energy – the sum of all the kinetic energies and potential energies of the particles within a substance. In an ideal gas, internal energy depends only on absolute temperature because there are no intermolecular forces.
内能 – 物质内所有粒子的动能与势能之和。在理想气体中，由于不存在分子间作用力，内能仅取决于绝对温度。
Specific heat capacity (c) – the energy required to raise the temperature of 1 kg of a substance by 1 K, without changing state. Units: J kg⁻¹ K⁻¹. Water has an unusually high specific heat capacity, which makes it an excellent coolant.
比热容 (c) – 在不改变物态的情况下，使 1 kg 物质升高 1 K 所需的能量。单位：J kg⁻¹ K⁻¹。水的比热容异常高，这使其成为优异的冷却剂。
Specific latent heat (L) – the energy required per kilogram to change the state of a substance at constant temperature. Latent heat of fusion (solid to liquid) and vaporisation (liquid to gas) are the two main types. 'Latent' means 'hidden' – energy goes into breaking bonds, not raising temperature.
比潜热 (L) – 在恒温下改变单位质量物质状态所需的能量。主要有熔化潜热（固→液）和汽化潜热（液→气）。“潜”的意思是“隐藏”——能量用于打破分子键，而非升高温度。
Absolute zero – the lowest possible temperature, 0 K or −273.15 °C, at which particles have minimum internal kinetic energy. All ideal-gas calculations rely on the Kelvin scale. Remember: 'Kelvin is King' for thermal physics.
绝对零度 – 可能的最低温度，0 K 或 −273.15 °C，此时粒子具有最小内动能。所有理想气体计算都依赖开尔文温标。记住：“热学计算用开氏”。
The ideal gas equation – te temperature. For N molecules it is written pV = NkT, where k is the Boltzmann constant.
理想气体方程 – 表示为 pV = nRT，联系压强、体积、摩尔数、摩尔气体常数和绝对温度。对于 N 个分子，可写为 pV = NkT，其中 k 是玻尔兹曼常数。
4. Electric and Magnetic Fields | 电场与磁场
Electric field strength (E) – a positive charge would move. For a uniform field between parallel plates, E = V/d. Link: 'Electric field tests with a tiny positive charge'.
电场强度 (E) – 单位正电荷所受的力，E = F/q。它是矢量，方向与正电荷移动方向一致。对于平行板间的匀强电场，E = V/d。记忆：“用微小正试探电荷测电场”。
Capacitance (C) – ds (F). A capacitor stores energy in the electric field between its plates. The energy stored can be expressed as ½QV or ½CV².
电容 (C) – 单位电势差存储的电荷量，C = Q/V，单位为法 (F)。电容器在极板间的电场中储存能量。储存的能量可表示为 ½QV 或 ½CV²。
Magnetic flux density (B) – rce on a current-carrying conductor: F = BIL sinθ. The unit is the tesla (T). Imagine B as 'how dense the magnetic field lines are'.
磁通量密度 (B) – 磁场强度的量度，由电流受力定义：F = BIL sinθ。单位是特斯拉 (T)。可把 B 想象为“磁感线有多密集”。
Faraday's law of electromagnetic induction – the magnitude of induced e.m.f. is directly proportional to the rate of change of magnetic flux linkage. The faster the flux changes, the greater the induced e.m.f.
法拉第电磁感应定律 – 感应电动势的大小与磁链变化率成正比。磁通量变化越快，感生电动势越大。
Lenz's law – n magnetic flux that produced it. This is why we insert a minus sign: ε = −d(NΦ)/dt. Think 'Lenz loves to oppose the change'.
楞次定律 – 感应电动势的方向总是阻碍产生它的磁通量变化。这正是公式中负号 ε = −d(NΦ)/dt 的缘由。记忆：“楞次喜欢对抗变化”。
5. Capacitance and Exponential Decay | 电容与指数衰减
Time constant (τ) – r an RC circuit, τ = RC, the time taken for the charge or voltage to fall to 1/e (about 37%) of its initial value during discharge. In one time constant, a capacitor achieves 63% of full charge when charging. 'RC – the time when things relax by about two-thirds'.
时间常数 (τ) – 对于 RC 电路，τ = RC，即放电时电荷或电压降至初始值 1/e（约 37%）所需的时间。充电时，一个时间常数内电容达到充满电量的 63%。联想：“RC —— 大致衰减三分之二的时间”。
Exponential decay – capacitor discharge, Q = Q₀ exp(−t/RC). The same mathematics describes radioactive decay.
指数衰减 – 某个量的减少速率与其当前值成正比的模式。电容放电时，Q = Q₀ exp(−t/RC)。同样的数学描述也适用于放射性衰变。
Charging curve – voltage across a charging capacitor follows V = V₀ (1 − exp(−t/RC)). The gradient of the V–t graph gives the rate of charging, which starts steeply and gradually flattens.
充电曲线 – 充电电容器两端的电压遵循 V = V₀ (1 − exp(−t/RC))。V–t 图的斜率表示充电速率，开始陡峭，逐渐平缓。
Energy stored in a capacitor – s stored in the electric field and can be released rapidly in a flash discharge. Remember: 'half the product – half the work'.
电容器储存的能量 – 三个等效表达式：E = ½QV = ½CV² = ½(Q²/C)。能量储存在电场中，可通过闪放电快速释放。记忆：“乘积的一半，做功的一半”。
6. Waves and Optics | 波动与光学
Progressive wave – a wave that transfers energy from one place to another without transferring matter. It may be transverse (oscillations perpendicular to direction of travel) or longitudinal (oscillations parallel). Light is transverse; sound is longitudinal.
行波 – 将能量从一处传至另一处的波，不传递物质。可以是横波（振动方向与传播方向垂直）或纵波（振动方向平行）。光是横波，声音是纵波。
Superposition – of the individual displacements. This leads to constructive and destructive interference. 'Superpose = add vectors'.
叠加 – 两列或多列波相遇时，任一点的合位移是各列波位移的矢量和。这产生相长干涉和相消干涉。“叠加即矢量相加”。
Coherence – two wave sources are coherent if they maintain a constant phase difference and have the same frequency. Only coherent sources produce a stable interference pattern. A laser is an excellent coherent light source.
相干性 – 若两个波源具有恒定的相位差和相同的频率，则它们是相干的。只有相干波源才能产生稳定的干涉图样。激光是极好的相干光源。
Path difference – interference in phase, path difference = nλ; for destructive, path difference = (n + ½)λ. 'Path difference tells you how waves line up'.
程差 – 两列波从各自波源传播到同一公共点所经距离的差值。同相相长干涉时，程差 = nλ；相消干涉时，程差 = (n + ½)λ。“程差决定波如何对齐”。
Diffraction – the spreading of waves when they pass through a gap or around an obstacle. The amount of diffraction increases when the gap width is comparable to the wavelength. 'Waves bend when openings end near their size'.
衍射 – 波通过缝隙或绕过障碍物时发生的展布现象。当缝隙宽度与波长可比时，衍射程度增加。“缝隙尺寸近波长，波动拐弯显衍射”。
7. Quantum Physics | 量子物理
Photon – a quantum of electromagnetic radiation, with energy E = hf, where h is Planck' ant. Photons travel at speed c in a vacuum and have zero rest mass. Think of a photon as a 'packet of
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