📚 Year 11 CIE Physics: Key Terms Memorisation Guide | Year 11 CIE 物理：词汇术语速记指南
Mastering physics starts with mastering its language. This article provides a structured, bilingual quick-reference list of essential CIE IGCSE / Year 11 Physics terms, paired with concise definitions and memory tips that will help you answer definition questions confidently and understand exam prompts. Read each term in English, then immediately reinforce it with the Chinese equivalent.
学好物理，首先要掌握它的语言。本文为你提供了一份结构化的双语速记指南，涵盖了 CIE IGCSE / Year 11 物理的核心术语。每个术语都配有精炼的定义和记忆技巧，助你自信应对定义题，轻松读懂考题。先读英文术语，立刻用中文释义强化记忆。
1. Scalars and Vectors | 标量与矢量
Scalar: A physical quantity that has magnitude (size) only, such as mass (kg), time (s), speed (m/s) and energy (J). Scalar quantities are added using ordinary arithmetic.
标量：只有大小（量值）的物理量，例如质量(kg)、时间(s)、速率(m/s)和能量(J)。标量用普通算术法则相加。
Vector: A quantity that has both magnitude and direction, e.g. displacement, velocity, acceleration and force. Vectors are represented by arrows; their length shows magnitude and the arrowhead shows direction. Remember: 'Vectors have direction, scalars just have size.'
矢量：既有大小又有方向的量，如位移、速度、加速度和力。矢量用箭头表示；长度代表大小，箭头代表方向。记忆口诀：“矢量有方向，标量只有量。”
Resultant force: The single force that has the same effect as all the individual forces acting on an object. If forces act along the same line, simply add or subtract; for perpendicular vectors, use Pythagoras’ theorem.
合力：与作用在物体上所有力效果相同的单个力。同一直线上的力直接相加或相减；垂直矢量则用勾股定理求解。
Equilibrium: State when the net force and net moment on an object are both zero. An object in equilibrium may be stationary or moving with constant velocity.
平衡：物体受到的合力和合力矩均为零的状态。处于平衡的物体可能静止，也可能做匀速直线运动。
2. Motion Graphs and Equations | 运动图像与方程
Distance-time graph: A plot of distance travelled against time. The gradient (slope) gives speed; a horizontal line indicates the object is at rest. Curved lines represent changing speed (acceleration).
距离-时间图像：距离随时间变化的图像。斜率表示速率；水平线段表示物体静止。曲线代表速度在变化（加速或减速）。
Speed-time graph: Graph of speed (or velocity) against time. The gradient gives acceleration; the area under the graph gives the distance travelled. A horizontal section means constant speed.
速度-时间图像：速度随时间变化的图像。斜率表示加速度；图像下的面积表示经过的距离。水平段表示匀速。
Acceleration: Rate of change of velocity. Formula: a = (v – u)/t, where v = final velocity, u = initial velocity, t = time. Unit: m/s².
加速度：速度的变化率。公式：a = (v – u)/t，其中 v 为末速度，u 为初速度，t 为时间。单位 m/s²。
Uniform acceleration equations at; s = ut + ½at²; v² = u² + 2as; s = ½(u+v)t. In exams, list the known quantities first.
匀变速直线运动公式：恒定加速下：v = u + at；s = ut + ½at²；v² = u² + 2as；s = ½(u+v)t。考试中先列出已知量。
3. Forces and Newton’s Laws | 力与牛顿定律
Newton’s First Law: An object remains at rest or in uniform motion in a straight line unless acted upon by an external resultant force. This explains inertia – the reluctance of an object to change its velocity.
牛顿第一定律：除非受到外力作用，否则物体将保持静止或匀速直线运动。这解释了惯性——物体抗拒速度变化的性质。
Newton’s Second Law rsely proportional to its mass: F = ma. Force is measured in newtons (N). 1 N = 1 kg·m/s².
牛顿第二定律：物体的加速度与合力成正比，与质量成反比：F = ma。力的单位是牛顿(N)，1 N = 1 kg·m/s²。
Newton’s Third Law: If body A exerts a force on body B, then body B exerts an equal and opposite force on body A. These are ‘action-reaction’ pairs, acting on different bodies.
牛顿第三定律：若物体A对物体B施加一个力，则B同时对A施加一个大小相等、方向相反的力。它们是“作用力与反作用力”对，作用在不同物体上。
Weight gravitational field strength (on Earth ≈ 9.8 N/kg). Weight is a vector; mass is a scalar.
重力：物体受到的引力，W = mg，g为重力场强度（地球约 9.8 N/kg）。重力是矢量，质量是标量。
4. Momentum and Impulse | 动量与冲量
Momentum (p) s a vector; its direction matches velocity. In a closed system, total momentum is conserved.
动量(p)：物体质量与速度的乘积：p = mv。单位 kg·m/s。动量是矢量，方向与速度一致。在封闭系统中总动量守恒。
Impulse p. The longer a force acts, the greater the change in momentum. Airbags and crumple zones increase impact time to reduce force.
冲量：动量的变化量：冲量 = F × t = Δp。力作用时间越长，动量变化越大。安全气囊和溃缩区通过延长碰撞时间来减小作用力。
Conservation of momentum no external resultant force acts. Use m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂ for two-body interactions.
动量守恒：在碰撞和爆炸中，若无外力作用，总动量前后相等。两体作用用公式 m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂。
5. Energy, Work and Power | 能量、功与功率
Energy ic and nuclear. Energy can be transferred but never created or destroyed (Law of Conservation of Energy).
能量：做功的本领。单位：焦耳(J)。主要能量形式：动能(KE = ½mv²)、重力势能(GPE = mgh)、热能、化学能、弹性势能和核能。能量可以转移但不会凭空产生或消失（能量守恒定律）。
Work done (W) arallel). 1 J = 1 N·m. No displacement in the direction of the force means zero work done.
做功(W)：力使物体移动时的能量转移：W = F × d（力与位移平行时）。1 J = 1 N·m。若在力的方向上无位移，则没有做功。
Power (P) P = E/t. Unit: watt (W); 1 W = 1 J/s. A powerful device transfers more energy per second.
功率(P)：做功或能量转移的速率：P = W/t 或 P = E/t。单位：瓦特(W)，1 W = 1 J/s。高功率设备每秒传递更多能量。
Efficiency : Ratio of useful energy output to total energy input, expressed as a percentage: Efficiency = (useful output ÷ input) × 100%. Always less than 100% due to thermal dissipation.
效率：有用输出能量与输入总能量之比，以百分比表示：效率 = (有用输出 ÷ 输入) × 100%。由于热耗散，效率总低于100% 。
6. Pressure and Density | 压强与密度
Pressure (p) Pa); 1 Pa = 1 N/m². The same force concentrated on a smaller area produces higher pressure – hence sharp knives cut easily.
压强(p)：单位面积上的力：p = F/A。单位帕斯卡(Pa)，1 Pa = 1 N/m²。相同力集中在较小面积上压强更大——所以锋利的刀更容易切割。
Pressure in a liquid ensity and g is gravitational field strength. Pressure increases with depth and acts equally in all directions at a given depth.
液体压强：p = hρg，h为深度，ρ为液体密度，g为重力场强度。压强随深度增加，且在相同深度朝各个方向大小相等。
Density (ρ) g/m³. Low-density materials float on high-density liquids. A balloon filled with helium floats because helium’s density is less than air’s.
密度(ρ)：单位体积的质量：ρ = m/V。单位 kg/m³。低密度材料浮在高密度液体上。氦气球上浮是因为氦气密度小于空气。
7. Thermal Physics Terms | 热物理术语
Temperature gy of particles in a substance. SI unit: kelvin (K), but Celsius (°C) is often used; 0 K = –273 °C (absolute zero).
温度：物质内粒子平均动能的量度。国际单位：开尔文(K)，常用摄氏度(°C)；0 K = –273 °C（绝对零度）。
Thermal expansion: Most solids, liquids and gases expand when heated. This occurs because particles vibrate more vigorously and move slightly further apart. Bimetallic strips use differential expansion.
热膨胀：多数物质受热时膨胀。因粒子振动加剧，间距略微增大。双金属片利用不同的膨胀率。
Specific heat capacity (c) cΔθ. Unit: J/(kg·°C). Water has a high specific heat capacity (4180 J/(kg·°C)), so it is an effective coolant.
比热容(c)：使1 kg物质温度升高1 °C所需的能量：Q = mcΔθ。单位：J/(kg·°C)。水的比热容很大(4180 J/(kg·°C))，因此是优良的冷却剂。
Latent heat: Energy absorbed or released during a change of state without a temperature change. Specific latent heat of fusion Lf (solid ↔ liquid) and vaporisation Lv (liquid ↔ gas). Q = mL.
潜热：物态变化时吸收或释放的能量，此时温度不变。熔化比潜热 Lf（固↔液）和汽化比潜热 Lv（液↔气）。Q = mL。
8. Wave Properties | 波的性质
Transverse wave: A wave where oscillations are perpendicular to the direction of wave travel. Examples: light, water ripples and all electromagnetic waves. Crests and troughs are clearly visible.
横波：振动方向与波传播方向垂直的波。例如：光、水波涟漪及所有电磁波。波峰和波谷明显可见。
Longitudinal wave: Oscillations are parallel to the direction of energy transfer. Sound and seismic P-waves are longitudinal. They consist of compressions and rarefactions.
纵波：振动方向平行于能量传递方向。声波和地震P波是纵波。由密部和疏部组成。
Frequency (f) r second. Unit: hertz (Hz). Period T = 1/f. Higher frequency means higher pitch for sound.
频率(f)：每秒完整振动的次数。单位：赫兹(Hz)。周期T = 1/f。声音频率越高，音调越高。
Wave speed equation requency (Hz) and λ wavelength (m). Speed depends on the medium; frequency is fixed by the source.
波速公式：v = fλ，v波速(m/s)，f频率(Hz)，λ波长(m)。波速由介质决定；频率由波源决定。
9. Light and Sound | 光与声
Reflection: Bouncing of a wave off a surface. Law of reflection: angle of incidence (i) equals angle of reflection (r), measured from the normal. Smooth surfaces give specular reflection; rough surfaces give diffuse reflection.
反射：波从表面弹回的现象。反射定律：入射角(i)等于反射角(r)，均从法线量起。光滑表面产生镜面反射，粗糙表面产生漫反射。
Refraction ends towards the normal when entering a denser medium. Refractive index n = sin i / sin r.
折射：波因速度改变而斜射穿过两种介质界面时发生的方向变化。光进入光密介质时向法线偏折。折射率 n = sin i / sin r。
Total internal reflection: Occurs when the angle of incidence in the denser medium is greater than the critical angle, and all light is reflected internally. Used in optical fibres and endoscopes.
全内反射：光密介质中入射角大于临界角时，光全部内反射而无折射的现象。用于光纤和内窥镜。
Sound: A longitudinal mechanical wave produced by vibrating objects. Requires a medium to travel; cannot pass through a vacuum. Echo is a reflected sound. Ultrasonic waves have frequency above 20 kHz and are used in sonar and cleaning.
声音：由振动体产生的纵波机械波。传播需要介质，不能在真空中传播。回声是反射的声音。超声频率高于20 kHz，用于声呐和清洗。
10. Electricity Basics | 电学基础
Current (I) /t. Unit: ampere (A). In metals, current is a flow of free electrons. Conventional current direction is from positive to negative, opposite to electron flow.
电流(I)：电荷的流动率：I = Q/t。单位：安培(A)。金属中电流是自由电子的流动。惯用电流方向为正电荷流动方向，与电子流动方向相反。
Potential difference (p.d., V) oints: V = W/Q. Measured in volts (V); 1 V = 1 J/C. It drives current through a component.
电压(V)：两点间单位电荷的能量转移量：V = W/Q。单位伏特(V)，1 V = 1 J/C。电压驱动电流通过元件。
Resistance (R) osition to current flow. Ohm’s law: V = IR at constant temperature. Resistors in series: Rtotal = R₁ + R₂ + …; in parallel: 1/Rtotal = 1/R₁ + 1/R₂ + … .
电阻(R)：对电流的阻碍作用。欧姆定律（恒温时）：V = IR。串联总电阻：Rtotal = R₁ + R₂ + …；并联：1/Rtotal = 1/R₁ + 1/R₂ + … 。
Electrical power P = V²/R. Unit: watt (W). A kilowatt-hour (kWh) is a unit of energy: 1 kWh = 3.6 × 10⁶ J.
电功率：电能转移的速率：P = IV，P = I²R 或 P = V²/R。单位瓦特(W)。千瓦时(kWh)是能量单位：1 kWh = 3.6 × 10⁶ J。
11. Magnetism and Electromagnetism | 磁学与电磁学
Magnetic field: Region around a magnet where a magnetic force is experienced. Field lines point from north to south outside the magnet. Arrowheads show direction; spacing indicates field strength.
磁场：磁体周围感受到磁力的区域。磁体外磁感线从北极指向南极。箭头表示方向；线间距表示磁场强度。
Electromagnet: A temporary magnet created by passing current through a coil of wire (solenoid), often with a soft iron core. Its magnetism can be switched on/off and strengthened by increasing current or number of turns.
电磁铁：电流流过线圈（螺线管）并通常插入软铁芯而产生的临时磁体。其磁性可通断，并通过增大电流或增加匝数来增强。
Motor effect rule gives force direction: thumb = force, first finger = field, second finger = current.
电动机效应：磁场中的载流导体（导线不平行于场）会受到力的作用。弗莱明左手定则确定力方向：拇指—力，食指—磁场，中指—电流。
Electromagnetic induction: A potential difference is induced across a conductor when it cuts magnetic field lines, or when the magnetic field through a coil changes. A coil and moving magnet form a simple generator.
电磁感应：导体切割磁感线或通过线圈的磁场变化时，导体两端会产生感应电压。线圈与移动磁铁构成简易发电机。
12. Radioactivity and Atomic Physics | 放射性及原子物理
Isotopes: Atoms of the same element with the same proton number (Z) but different nucleon (mass) numbers (A). They have identical chemical properties because electron arrangement is identical.
同位素：质子数(Z)相同而核子数(质量数A)不同的同种元素原子。因电子排布相同，它们的化学性质相同。
Radioactive decay: Spontaneous emission of radiation from an unstable nucleus. Three types: alpha (α, helium nucleus, 2p + 2n, highly ionising, low penetration), beta (β⁻, fast electron, moderate ionising), and gamma (γ, electromagnetic wave, high penetration).
放射性衰变：不稳定的原子核自发地发射辐射。三种类型：α（氦核，2p+2n，电离能力强，穿透力弱），β⁻（高速电子，中等电离），γ（电磁波，穿透力极强）。
Half-life: Time taken for half the radioactive nuclei in a sample to decay. It is a constant for a given isotope. Background radiation must be subtracted from count-rate measurements.
半衰期：样品中一半放射性原子核发生衰变所需的时间。对给定同位素是常数。测量计数率时必须减去本底辐射。
Nuclear equations: In alpha decay, mass number decreases by 4, atomic number by 2. In beta decay, mass number unchanged, atomic number increases by 1. Total nucleon and proton numbers are conserved.
核方程：α衰变质量数减4，原子序数减2。β衰变质量数不变，原子序数加1。核子总数和质子数守恒。
Uses of radioisotopes: Smoke detectors (americium-241 emits α), thickness gauging (beta), medical tracers and radiotherapy (gamma, e.g. cobalt-60). Safety: keep sources shielded, limit exposure time, never point directly at a person.
放射性同位素的应用：烟雾报警器（镅-241放出α），厚度测量（β），医疗示踪和放射治疗（γ，如钴-60）。安全：遮蔽放射源，限制暴露时间，切勿对向人体。
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