📚 Year 12 CAIE Physics: Vocabulary & Terminology Quick-Memorisation Guide | Year 12 CAIE 物理：词汇术语速记指南
Mastering the technical vocabulary in Year 12 CAIE Physics is half the battle. This guide breaks down the most essential terms across the syllabus into simple, memorable explanations, pairing precise English definitions with clear Chinese equivalents and memory hooks. By connecting each term to how it actually behaves in equations or experiments, you will find it much easier to recall during exams and apply correctly in structured questions.
在 CAIE Year 12 物理中，掌握专业术语就等于成功了一半。本指南将考纲中最核心的词汇拆解成简单好记的解释，用准确的英文定义配上清晰的中文对应和记忆钩子。把每个术语与它在方程或实验中的实际表现联系起来，你会发现考试时更容易想起，也能在结构化问题中准确运用。
1. Kinematics | 运动学
Displacement (s) is a vector quantity representing the straight-line distance from the starting point to the finishing point in a specified direction. It is measured in metres (m).
位移 (s) 是矢量，表示从起点到终点的直线距离并带有明确方向，单位为米 (m)。记住它与 distance 不同，distance 只有大小没有方向。
Velocity change of displacement with respect to time, also a vector. Average velocity v = Δs / Δt.
速度 (v) 是位移的时间变化率，同样是矢量。平均速度 v = Δs / Δt。注意区分 speed（速率），speed 是标量。
Acceleration f change of velocity. In uniformly accelerated motion, a = (v - u)/t. The SI unit is m/s².
加速度 (a) 是速度的变化率。匀加速运动中 a = (v - u)/t，单位是 m/s²。自由落体的加速度约 9.81 m/s²，方向竖直向下。
2. Dynamics | 动力学
Newton's First Law: An object will remain at rest or move with constant velocity unless acted upon by a resultant (unbalanced) external force.
牛顿第一定律：物体将保持静止或匀速直线运动状态，除非受到合外力（非平衡力）的作用。这也称为惯性定律。
Linear momentum ts conservation law is crucial in collisions: the total momentum before equals total momentum after, provided no external resultant force acts.
线动量 (p) 是质量与速度的乘积，p = mv，是矢量。动量守恒定律在碰撞中至关重要：只要没有合外力作用，碰撞前后总动量不变。
Impulse by the time for which it acts: Impulse = FΔt = Δp. This links force with momentum change.
冲量 是动量的变化量，也等于平均合外力乘以作用时间：冲量 = FΔt = Δp。这解释了安全气囊为什么能减小冲击力——延长碰撞时间。
3. Forces and Equilibrium | 力与平衡
Weight t, W = mg, always directed towards the centre of the Earth. It is measured in newtons (N).
重力 (W) 是作用于物体上的引力，W = mg，方向总是指向地心，单位是牛顿 (N)。质量 mass 是标量，单位 kg，不要混淆。
Centre of gravity is the point from which the entire weight of an object appears to act. For a uniform regular shape, it is at the geometrical centre.
重心 是物体所受重力的等效作用点。对于均匀规则形状，重心位于几何中心。悬挂法可以用来找出不规则物体的重心。
Moment of a force ents states that for equilibrium, sum of clockwise moments = sum of anticlockwise moments.
力矩 是对转轴的力×力臂（垂直距离）。力矩平衡原理：平衡时顺时针力矩之和等于逆时针力矩之和。这是解决杠杆系统问题的核心。
4. Work, Energy and Power | 功、能与功率
Work done s cosθ. When force and displacement are parallel, W = F s. It is a scalar, unit joule (J).
功 (W) 等于力与沿力方向的位移之积：W = F s cosθ。当力与位移平行时 W = F s，是标量，单位焦耳 (J)。能量转化了多少就等于做了多少功。
Kinetic energy (K.E. or Eₖ) = ½ m v². This is the energy an object possesses due to its motion.
动能 (Eₖ) = ½ m v²，是物体因运动而具有的能量。碰撞时动能不一定守恒，只有完全弹性碰撞才守恒。
Gravitational potential energy (GPE or Eₚ) = m g Δh, the energy stored due to an object's position in a gravitational field. The zero level can be chosen arbitrarily.
重力势能 (Eₚ) = m g Δh，是因物体在重力场中的位置而储存的能量。零势能面可任意选取，重要的是势能变化量。
Power f doing work or transferring energy: P = W / t = F v, where v is velocity. Unit: watt (W).
功率 (P) 是做功或能量转换的速率：P = W / t = F v，其中 v 是速度，单位瓦特 (W)。发动机功率一定时，牵引力与速度成反比。
5. Circular Motion | 圆周运动
Angular displacement (θ) is the angle swept out by a radius, measured in radians (rad). 2π rad = 360°.
角位移 (θ) 是半径扫过的角度，单位为弧度 (rad)。弧度制下 s = r θ，让计算更简洁。
Centripetal acceleration rds the centre of the circle. It arises from a net centripetal force, not a separate force itself.
向心加速度 (a) = v² / r = ω² r，始终指向圆心。它来自于向心力，本身不是单独的力。转弯、卫星轨道都依赖向心力。
Centripetal force force causing centripetal acceleration; it can be tension, friction, gravity, or a component of normal force.
向心力 (F) = m v² / r = m ω² r，是使物体产生向心加速度的合外力，可以是张力、摩擦力、引力或支持力的分量。没有所谓的“离心力”施力物体。
6. Waves Basics | 波的基础
Transverse wave: a wave in which the particle displacement is perpendicular to the direction of energy propagation. Example: light, water ripples.
横波：质点振动方向与能量传播方向垂直。例如光波、水波涟漪。电磁波都是横波。
Longitudinal wave: particle displacement is parallel to the direction of energy propagation. Sound waves in air are longitudinal, consisting of compressions and rarefactions.
纵波：质点振动方向与能量传播方向平行。声波在空气中是纵波，由疏密相间的区域组成。
Frequency (f) is the number of complete oscillations per second, unit hertz (Hz). Period T = 1/f.
频率 (f) 是每秒完成的全振动次数，单位赫兹 (Hz)。周期 T = 1/f。波的频率由波源决定，与介质无关。
Wavelength ce between two consecutive points in phase (e.g. two adjacent crests). Wave speed v = f λ.
波长 (λ) 是相邻两个同相位点之间的距离（如相邻波峰）。波速 v = f λ，该关系对所有波都适用。
7. Superposition and Interference | 叠加与干涉
Principle of superposition: when two or more waves meet at a point, the resultant displacement is the vector sum of the individual displacements.
叠加原理：两列或以上波在一点相遇时，合位移等于各波位移的矢量和。这解释了干涉和驻波的形成。
Constructive interference a resultant amplitude that is the sum of the individual amplitudes. Path difference = nλ.
相长干涉 发生当波同相到达，合振幅为各振幅之和，程差 = nλ（n 为整数）。亮纹、强信号都是相长干涉。
Destructive interference of occurs when waves are exactly out of phase (180° phase difference), giving a minimum amplitude. Path difference = (n + ½)λ.
相消干涉 当波完全反相（相位差 180°）时发生，合振幅最小甚至为零。程差 = (n + ½)λ。
Stationary (standing) wave: formed by superposition of two progressive waves of equal amplitude and frequency travelling in opposite directions. Nodes are points of zero displacement; antinodes have maximum amplitude.
驻波（定波）：由两列频率、振幅相同但传播方向相反的行波叠加而成。波节处位移始终为零，波腹处振幅最大。
8. Electricity: Basic Quantities | 电学基本量
Electric current / Δt, unit ampere (A). Conventional current flows from positive to negative, opposite to electron flow.
电流 (I) 是电荷流动的速率，I = ΔQ / Δt，单位安培 (A)。传统电流方向是从正到负，与电子流动方向相反。
Potential difference gy transferred per unit charge as it moves between those points. V = W / Q, unit volt (V).
电位差（电压） (V) 是单位电荷在两点间移动时转移的能量，V = W / Q，单位伏特 (V)。电池电动势 emf 是电源将其他形式能量转化为电能的电压。
Resistance (R) of a component is defined by R = V / I, unit ohm (Ω). Ohm's law states that for a metallic conductor at constant temperature, V ∝ I, thus R is constant.
电阻 (R) = V / I，单位欧姆 (Ω)。欧姆定律指出，对于温度恒定的金属导体，电压与电流成正比，因此 R 恒定。灯丝电阻会随温度升高而增加。
Resistivity stance to geometry: R = ρ L / A. Unit: Ω m. Copper has low resistivity; nichrome has high.
电阻率 (ρ) 是材料的固有属性，R = ρ L / A，单位 Ω m。铜电阻率低，镍铬合金电阻率高，因而用作发热元件。
9. DC Circuits | 直流电路
Kirchhoff's first law (junction rule) ents entering a junction = sum of currents leaving. This expresses conservation of charge.
基尔霍夫第一定律（节点定律）：进入节点的电流之和等于离开的电流之和。它是电荷守恒的体现。
Kirchhoff's second law (loop rule): in any closed loop, the algebraic sum of emfs equals the sum of p.d.s across components. Energy conservation.
基尔霍夫第二定律（回路定律）：任意闭合回路中，电动势的代数和等于各元件上电压降的代数和。基于能量守恒。
Internal resistance f a power source causes the terminal p.d. to drop under load: V = E - I r, where E is emf. 'Lost volts' = I r.
内阻 (r) 使得电源端电压在接负载时下降：V = E - I r，其中 E 为电动势，'lose voltage' 等于 I r。内阻通常很小但不可忽略。
Potential divider oltage: Vₒᵤₜ = [R₂ / (R₁ + R₂)] × Vᵢₙ. Widely used with sensors like thermistors and LDRs.
分压器 利用两个电阻串联，输出输入电压的一部分：Vₒᵤₜ = [R₂ / (R₁ + R₂)] × Vᵢₙ。常与热敏电阻、光敏电阻组合用于传感电路。
10. Particle and Nuclear Physics | 粒子与核物理
Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons, hence different mass numbers.
同位素 是质子数相同但中子数不同的同种元素原子，因此质量数不同。碳-12 和碳-14 是常见的同位素。
Alpha particle (α) is a helium nucleus, ⁴₂He, consisting of 2 protons and 2 neutrons. It has low penetration (stopped by paper) and strong ionising power.
α 粒子 是氦原子核 ⁴₂He，包含 2 个质子和 2 个中子。穿透力弱（纸张即可阻挡），电离能力强。
Beta particle on emitted from a neutron-rich nucleus when a neutron decays into a proton: n → p + e⁻ + ν̄ₑ. Moderate penetration, stopped by aluminium.
β⁻ 粒子 是高速电子，当中子衰变成质子时从核内放出：n → p + e⁻ + ν̄ₑ。穿透力中等，铝板可阻挡。
Gamma radiation (γ) is electromagnetic radiation of very short wavelength, emitted from an excited nucleus. Excellent penetration, reduced by thick lead or concrete.
γ 射线 是高能电磁辐射，从激发态原子核发出。穿透力极强，需要厚铅板或混凝土才能显著衰减。
Activity of decays per unit time, measured in becquerels (Bq). It decreases exponentially: A = λ N.
放射性活度 (A) 是单位时间内衰变的次数，单位贝可 (Bq)。活度随时间呈指数衰减：A = λ N。
Half-life (t₁/₂) is the average time taken for half the unstable nuclei in a sample to decay, or for the activity to halve.
半衰期 (t₁/₂) 是样品中一半不稳定的原子核发生衰变、或活度减半所需的平均时间。它不受温度、压力等外部条件影响。
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