Year 12 OCR Physics: A Mnemonic Terminology Guide | Year 12 OCR 物理：词汇术语速记指南

📚 Year 12 OCR Physics: A Mnemonic Terminology Guide | Year 12 OCR 物理：词汇术语速记指南

Mastering the language of physics is half the battle. This guide presents key terms from the Year 12 OCR specification with simple definitions, memorable tricks, and paired English–Chinese explanations. Use it as a quick-reference flashcard deck to cement your understanding before exams.

掌握物理的语言是成功的一半。本指南精选 Year 12 OCR 考纲中的核心术语，给出简明定义和速记技巧，并配以中英双语解释。你可以把它当作闪卡合集，在考前快速巩固理解。

1. Measurement & Uncertainty Keywords | 测量与不确定度关键词

SI base units – the seven fundamental units (metre, kilogram, second, ampere, kelvin, mole, candela) from which all others are derived. Think of them as the ‘alphabet of measurement’. Memory hook: ‘Most Kings Seldom Allow Keen Men Chocolate’ – metre, kilogram, second, ampere, kelvin, mole, candela.

SI 基本单位 – 七个基本单位（米、千克、秒、安培、开尔文、摩尔、坎德拉），所有其他单位都由它们导出。它们是“测量的字母表”。记忆口诀：“米千秒安开摩坎”。

Homogeneity of equations – every term in a physical equation must have the same base units. This is the ultimate algebra check. Mnemonic: ‘If it’s not homogeneous, the equation is broken.’

方程的同次性 – 物理方程中每一项都必须具有相同的基本单位组合。这是终极的代数检验。口诀：“不同次的方程一定错”。

Precision – how close repeated measurements are to each other; related to the spread of data, not the true value. Think: ‘Precision is about repetition – tight grouping.’

精密度 – 重复测量结果彼此之间有多接近；与数据的分散程度有关，而非与真值的关系。记忆：“精密看重复，点越密越好”。

Accuracy – how close a measurement is to the accepted true value. Remember: ‘Accuracy is about truth, precision is about tightness.’

准确度 – 测量值离公认真值有多近。口诀：“准确看真值，精密看离差”。

Absolute uncertainty – the interval within which the true value is expected to lie, expressed with the same units as the measurement. E.g. 5.0 ± 0.2 cm. Visualise it as the ‘error bar’.

绝对不确定度 – 预期真值所在的区间，单位与测量值相同，如 5.0 ± 0.2 cm。可把它想象成“误差棒”。

Percentage uncertainty – (absolute uncertainty / measured value) × 100%. It tells you how serious the uncertainty is relative to the measurement. Think: ‘Percentage uncertainty = percentage of doubt.’

百分不确定度 – (绝对不确定度 / 测量值) × 100%。它告诉你不确定度相对于测量值有多严重。记忆：“百分不确定度就是怀疑的百分比”。

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2. Kinematics Essentials | 运动学要点

Displacement – vector quantity; the straight-line distance from start to finish in a given direction. Mnemonic: ‘Displacement tells you how far out of place an object is.’

位移 – 矢量；从起点到终点的直线距离，带方向。口诀：“位移是偏离原位的带有方向的直线距离”。

Velocity – rate of change of displacement:

v = Δs / Δt

. Velocity is speed with an attitude (direction).

速度 – 位移的变化率：v = Δs / Δt。速度就是带方向的速度大小。

Acceleration – rate of change of velocity:

a = Δv / Δt

. Even deceleration is just acceleration in the opposite direction.

加速度 – 速度的变化率：a = Δv / Δt。减速不过是反方向的加速度。

Free fall – motion under gravity alone, with acceleration g = 9.81 m s⁻² (on Earth). All objects fall at the same rate in the absence of air resistance. Recall Galileo’s thought experiment.

自由落体 – 仅在重力作用下的运动，加速度 g = 9.81 m s⁻²（地球表面）。没有空气阻力时所有物体下落速度相同。回想伽利略的思想实验。

Projectile motion – horizontal and vertical components of motion are independent. Horizontal velocity stays constant; vertical acceleration is g. The key: treat the two components separately.

抛体运动 – 水平与竖直运动分量相互独立。水平速度不变；竖直加速度为 g。关键：将两个方向分开处理。

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3. Dynamics & Newton’s Laws | 动力学与牛顿定律

Inertia – the tendency of an object to resist changes in its state of motion. It is mass that gives inertia. More mass = harder to accelerate.

惯性 – 物体抵抗运动状态变化的性质。质量是惯性的量度。质量越大，越难加速。

Newton’s First Law – an object remains at rest or moves with constant velocity unless acted on by a resultant force. Think: ‘No net force, no change.’

牛顿第一定律 – 若无合力作用，物体保持静止或匀速直线运动。口诀：“无合力，无变化”。

Newton’s Second Law –

F = m a

. The net force equals mass times acceleration. Acceleration is directly proportional to force and inversely proportional to mass.

牛顿第二定律 – F = m a。合力等于质量乘加速度。加速度与力成正比，与质量成反比。

Newton’s Third Law – for every action force there is an equal and opposite reaction force. The forces act on different bodies. Use: ‘A on B equals B on A.’

牛顿第三定律 – 每一个作用力都有一个等大反向的反作用力，作用在不同物体上。口诀：“A对B的力等于B对A的力”。

Momentum – product of mass and velocity:

p = m v

. Momentum is a vector and is conserved in closed systems. ‘Mass in motion.’

动量 – 质量与速度的乘积：p = m v。动量是矢量，在封闭系统中守恒。记忆：“运动中的质量”。

Impulse – change in momentum caused by a force acting over a time interval:

F Δt = Δp

. The area under a force–time graph gives impulse.

冲量 – 力在一定时间内造成的动量变化：F Δt = Δp。力–时间曲线下的面积就是冲量。

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4. Work, Energy & Power | 功、能量与功率

Work done – energy transferred when a force moves an object:

W = F x cosθ

. Only the component of force in the direction of motion does work. ‘Work is force with a purpose.’

功 – 力使物体移动时传递的能量：W = F x cosθ。只有力沿运动方向的分量才做功。记忆：“做功的力是有方向的”。

Kinetic energy (KE) – energy due to motion:

KE = ½ m v²

. The squared velocity means speed counts more than mass.

动能 – 因运动而具有的能量：KE = ½ m v²。速度的平方意味着速度比质量对动能的影响更大。

Gravitational potential energy (GPE) – energy due to height in a gravitational field:

GPE = m g h

. The ‘h’ is measured from an arbitrary zero level.

重力势能 – 因在重力场中的高度而具有的能量：GPE = m g h。高度 h 是从任意选定的零势能面起算的。

Conservation of energy – energy cannot be created or destroyed, only transferred into different forms. The total energy in an isolated system is constant. Think of it as an energy ‘budget’.

能量守恒 – 能量不会凭空产生或消失，只能从一种形式转化为另一种形式。孤立系统的总能量恒定。就像能量“账户”。

Power – rate of energy transfer:

P = ΔW / Δt = F v

. The unit is the watt (J s⁻¹). ‘Power is how fast you do work.’

功率 – 能量传递的速率：P = ΔW / Δt = F v。单位是瓦特 (J s⁻¹)。记忆：“功率就是做功的快慢”。

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5. Materials & Mechanical Properties | 材料与力学性质

Hooke’s Law – extension of a spring is directly proportional to the applied force, up to the limit of proportionality:

F = k Δx

. k is the spring constant (N m⁻¹).

胡克定律 – 在比例极限内，弹簧的伸长量与施加的力成正比：F = k Δx。k 为劲度系数 (N m⁻¹)。

Elastic limit – the maximum stress that can be applied without causing permanent deformation. Beyond it the material won’t return to its original shape.

弹性极限 – 不引起永久形变所能施加的最大应力。超过该点，材料将无法恢复原状。

Plastic deformation – permanent change in shape that remains after the load is removed. Compare: ‘Plastic = Permanent.’

塑性形变 – 卸载后残留的永久形状变化。联想记忆：“塑性 – 永久性”。

Stress – force per unit cross-sectional area:

σ = F / A

. Unit is pascal (Pa). Stress is the cause of deformation.

应力 – 单位截面面积上的力：σ = F / A。单位为帕斯卡 (Pa)。应力是形变的原因。

Strain – extension per unit original length:

ε = ΔL / L₀

. Strain has no units; it is a ratio.

应变 – 单位原长的伸长量：ε = ΔL / L₀。应变无单位，是一个比率。

Young modulus – ratio of stress to strain in the linear region:

E = σ / ε

. It measures stiffness. A high Young modulus means the material is hard to stretch.

杨氏模量 – 线弹性区域内应力与应变的比值：E = σ / ε。它衡量刚度，杨氏模量越大，材料越难拉伸。

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6. Electricity Fundamentals | 电学基础

Electric current – rate of flow of charge:

I = ΔQ / Δt

. Unit: ampere (A). Conventional current flows from positive to negative.

电流 – 电荷流动的速率：I = ΔQ / Δt。单位：安培 (A)。约定电流方向为正电荷移动方向。

Potential difference (voltage) – energy transferred per unit charge:

V = W / Q

. Think: ‘Voltage is electrical pressure.’

电势差（电压） – 每单位电荷转移的能量：V = W / Q。想象成“电的压力”。

Resistance – opposition to current:

R = V / I

. Unit: ohm (Ω). Ohm’s Law holds when resistance is constant (at constant temperature).

电阻 – 对电流的阻碍：R = V / I。单位：欧姆 (Ω)。当温度恒定且电阻不变时，欧姆定律成立。

Resistivity – a material property linking resistance to geometry:

R = ρ L / A

. ρ (rho) depends only on material and temperature.

电阻率 – 联系电阻与几何尺寸的材料属性：R = ρ L / A。ρ 只取决于材料和温度。

Electromotive force (emf) – energy supplied by a source per unit charge, measured in volts. It is the ‘total push’ available, some of which is lost across internal resistance.

电动势 – 电源每单位电荷提供的能量，单位伏特。它是可提供的“总推动力”，其中一部分消耗在内阻上。

Internal resistance (r) – resistance inside a power source causing terminal voltage to drop as current increases:

V = ε – I r

.

内阻 – 电源内部的电阻，导致路端电压随电流增大而下降：V = ε – I r。

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7. Circuits & Electrical Power | 电路与电功率

Series circuit – components connected end-to-end; current is the same everywhere, voltage divides. Remember: ‘Series shares voltage.’

串联电路 – 元件首尾相接；各处电流相等，电压分配。口诀：“串联分压”。

Parallel circuit – components connected side-by-side; voltage is the same across branches, current splits. ‘Parallel shares current.’

并联电路 – 元件并排连接；各支路电压相等，电流分流。口诀：“并联分流”。

Kirchhoff’s first law – conservation of charge: total current entering a junction equals total current leaving. Think of water pipes: flow in = flow out.

基尔霍夫第一定律 – 电荷守恒：进入节点的总电流等于离开节点的总电流。联想水管：流入等于流出。

Kirchhoff’s second law – conservation of energy: sum of emfs around any closed loop equals sum of potential drops. ‘Loop law’ – energy given = energy taken.

基尔霍夫第二定律 – 能量守恒：沿任一闭合回路，电动势代数和等于电势降代数和。“回路定律”：提供的能量 = 消耗的能量。

Potential divider – two resistors in series splitting voltage proportionally:

V_out = V_in × (R₂ / (R₁ + R₂))

. Smooth control of voltage using variable resistors.

分压器 – 两个电阻串联，按比例分配电压：V_out = V_in × (R₂ / (R₁ + R₂))。通过可变电阻实现电压的平滑调节。

Power dissipation – rate at which a component converts electrical energy:

P = I V = I² R = V² / R

. Heating in a resistor is why devices get warm.

功率耗散 – 元件将电能转化为其他形式能量的速率：P = I V = I² R = V² / R。电阻发热就是功率耗散的表现。

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8. Waves Overview | 波动概要

Amplitude (A) – maximum displacement from equilibrium. For a transverse wave, it’s the crest height. Without amplitude, there is no wave carrying energy.

振幅 – 偏离平衡位置的最大位移。对于横波，就是波峰的高度。没有振幅就没有携带能量的波。

Wavelength (λ) – distance between two consecutive points in phase (e.g. crest to crest). It’s the spatial period of the wave.

波长 – 两个相邻同相点（如波峰到波峰）之间的距离。是波的空间周期。

Frequency (f) – number of complete oscillations per second, measured in hertz (Hz). High frequency means high pitch for sound.

频率 – 每秒完整振动的次数，单位赫兹 (Hz)。高频对应高音调。

Wave speed (v) – how fast the disturbance travels:

v = f λ

. Speed depends on the medium for mechanical waves.

波速 – 扰动传播的快慢：v = f λ。机械波的波速取决于介质。

Transverse vs longitudinal – in transverse waves, oscillations are perpendicular to energy transfer (light, water). In longitudinal waves, oscillations are parallel (sound). Mnemonic: ‘Transverse is like a side-to-side wave; longitudinal compressions go along.’

横波与纵波 – 横波中振动方向与能量传递方向垂直（光波、水波）；纵波中振动方向平行（声波）。口诀：“横波振动横着走，纵波疏密顺着走”。

Superposition – when two waves meet, the resultant displacement is the vector sum of individual displacements. At constructive interference crests coincide; at destructive interference crest meets trough.

叠加 – 两列波相遇时，合位移是各位移的矢量和。相长干涉波峰相遇；相消干涉波峰与波谷相遇。

Stationary wave – formed by superposition of two identical waves travelling in opposite directions. Nodes (no displacement) and antinodes (maximum displaced) are fixed in space.

驻波 – 由两列相同、相向而行的波叠加而成。节点（零位移）和腹点（最大位移）在空间固定不动。

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9. Quantum Phenomena | 量子现象

Photon – a discrete packet of electromagnetic energy:

E = h f

. Light behaves as both a wave and a stream of particles. Remember: ‘Photon energy = Planck’s constant × frequency.’

光子 – 电磁能量的不连续包：E = h f。光既表现为波，也表现为粒子流。记忆：“光子能量 = 普朗克常数 × 频率”。

Photoelectric effect – emission of electrons from a metal surface when light of sufficient frequency shines on it. One photon ejects one electron if energy exceeds the work function.

光电效应 – 当频率足够高的光照射金属表面时，电子被发射出来。一个光子若能量大于功函数，可以逐出一个电子。

Work function (Φ) – minimum energy needed to remove an electron from the surface of a metal. Think of it as the ‘electron escape fee’.

功函数 – 从金属表面移走一个电子所需的最小能量。想象成“电子的逃逸费”。

Threshold frequency (f₀) – minimum frequency of light to cause photoemission:

h f₀ = Φ

. Below this frequency, no electrons are emitted regardless of intensity.

阈值频率 – 产生光电发射的最低光频率：h f₀ = Φ。低于此频率，无论光强多大，都没有电子逸出。

Electronvolt (eV) – energy unit for atomic scales: 1 eV = 1.6 × 10⁻¹⁹ J. The energy gained by an electron moving through 1 V. Handy for photon energies.

电子伏特 – 原子尺度的能量单位：1 eV = 1.6 × 10⁻¹⁹ J，是一个电子经过 1 V 电势差获得的能量。光子能量常用它表示。

Energy levels – discrete energy states that electrons can occupy in an atom. Transitions between levels produce photons of specific energies, giving line spectra.

能级 – 原子中电子可以占据的分立能量状态。能级间的跃迁发射特定能量的光子，产生线状光谱。

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10. Practical Skills & Graph Language | 实验技能与图线语言

Independent variable – the variable you deliberately change in an experiment (plotted on x-axis). ‘I change it.’

自变量 – 实验中你主动改变的变量（画在 x 轴）。记忆：“我改变的”。

Dependent variable – the variable you measure; it depends on the independent variable (plotted on y-axis). ‘It depends on what I change.’

因变量 – 你测量的量，它依赖于自变量（画在 y 轴）。记忆：“它取决于我的改变”。

Systematic error – an error that shifts all readings by a fixed amount (e.g. zero error). It affects accuracy but not precision. Fix it by calibration.

系统误差 – 使所有读数偏移固定量的误差（如零点误差）。它影响准确度但不影响精密度。可通过校准消除。

Random error – unpredictable scatter due to human or environmental factors; reduces precision. Take more readings and use averages to compensate.

随机误差 – 由于人为或环境因素造成的不可预测的散布；降低精密度。多次读数取平均可减小影响。

Gradient – rate of change of y with respect to x:

gradient = Δy / Δx

. In physics, gradients often represent meaningful quantities (e.g. velocity, acceleration, resistance).

斜率 – y 相对于 x 的变化率：斜率 = Δy / Δx。在物理中，斜率常代表有意义的物理量（如速度、加速度、电阻）。

Intercept – the value of y when x = 0. It may represent an initial condition or a systematic offset. Check if it should be zero – if not, explain why.

截距 – 当 x = 0 时 y 的值。它可能代表初始条件或系统偏移。检查它是否应为零，如果不是，要解释原因。

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