A-Level Physics: Final Revision Guide | A-Level 物理：期末复习提纲

📚 A-Level Physics: Final Revision Guide | A-Level 物理：期末复习提纲

As your A-Level Physics exam approaches, a structured revision plan is essential. This guide summarises the core topics, key equations and common pitfalls to help you consolidate your understanding and perform with confidence.

随着A-Level物理考试临近，制定系统的复习计划至关重要。本提纲总结了核心主题、关键方程和常见易错点，帮助你巩固理解、自信应考。

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1. Mechanics: Kinematics & Dynamics | 力学：运动学与动力学

Kinematics describes motion without reference to its causes. Key quantities include displacement (s), velocity (v) and acceleration (a). For constant acceleration, the SUVAT equations link these quantities over time (t). Remember that acceleration is the gradient of a velocity-time graph, and displacement is the area under it.

运动学描述运动而不涉及成因。关键量包括位移(s)、速度(v)和加速度(a)。对于匀加速，SUVAT方程将这些量与时间(t)联系起来。记住加速度是速度-时间图的斜率，位移是其下面积。

v = u + at   s = ut + ½at²   v² = u² + 2as   s = ½(u+v)t

Dynamics is governed by Newton’s laws: N1 – a body remains at rest or in uniform motion unless acted upon by a resultant force. N2 – F = ma, where F is the resultant force. N3 – forces occur in equal and opposite pairs. Free-body diagrams are crucial for resolving forces and determining net acceleration.

动力学由牛顿定律支配：第一定律 – 除非受合外力作用，物体保持静止或匀速直线运动；第二定律 – F = ma，F为合外力；第三定律 – 力成对出现且等大反向。受力图对于分解力和确定合加速度至关重要。

Always assign a consistent positive direction when solving problems involving vectors. Watch out for sign errors with acceleration due to gravity; g is often taken as 9.81 m s⁻² downwards.

在解决矢量问题时，务必统一规定正方向。注意重力加速度的符号错误；通常设向下为正，g = 9.81 m s⁻²。

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2. Forces, Energy & Work | 力、能量与功

Work done (W = Fs cosθ) transfers energy. Kinetic energy (½mv²) and gravitational potential energy (mgh) are conserved in the absence of dissipative forces. Power is the rate of work (P = W/t = Fv). In collisions, momentum (p = mv) is always conserved; distinguish elastic (KE conserved) and inelastic collisions.

做功(W = Fs cosθ)转移能量。在无耗散力时，动能(½mv²)和重力势能(mgh)守恒。功率是做功的快慢(P = W/t = Fv)。碰撞中动量(p = mv)始终守恒；区分弹性碰撞（动能守恒）和非弹性碰撞。

Conservation of momentum: m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

Impulse is the change in momentum: FΔt = Δp. The area under a force–time graph gives the impulse. Efficiency = useful energy output / total energy input.

冲量等于动量的变化：FΔt = Δp。力-时间图下的面积代表冲量。效率 = 有用能量输出 / 总能量输入。

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3. Materials & Properties of Matter | 材料与物质性质

Stress (σ = F/A) and strain (ε = ΔL/L) describe material deformation. The Young modulus E = σ/ε applies within the elastic limit. A force–extension graph shows a linear Hooke’s law region, followed by plastic deformation and fracture. The gradient of the linear part gives the spring constant k, and the area under the curve represents energy stored.

应力(σ = F/A)和应变(ε = ΔL/L)描述材料变形。弹性限度内杨氏模量E = σ/ε。力-伸长图显示线性胡克定律区域，随后发生塑性变形和断裂。线性部分的斜率给出劲度系数k，曲线下面积代表储存的能量。

For a spring: F = kΔx   energy stored = ½FΔx = ½k(Δx)²

Brittle materials fracture with little plastic deformation, while ductile materials undergo significant plastic flow. The yield point and ultimate tensile stress are key features on a stress-strain graph.

脆性材料在很小塑性变形下就断裂，而延性材料有显著的塑性流动。屈服点和极限抗拉应力是应力-应变图上的关键特征。

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4. Waves & Oscillations | 波与振动

Waves transfer energy without net mass transport. Key relationship: v = fλ. Phase difference and path difference determine interference patterns. Young’s double-slit: Δx = λD / s. Stationary waves arise from the superposition of identical travelling waves, with nodes (zero displacement) and antinodes (maximum displacement). Diffraction is greatest when the gap width ≈ λ.

波传递能量而无净质量传输。关键关系：v = fλ。相位差和路程差决定干涉图样。杨氏双缝：Δx = λD/s。驻波由相同行波叠加形成，存在波节（位移为零）和波腹（位移最大）。当缝隙宽度约等于波长时，衍射最显著。

Polarisation is evidence for transverse waves; only transverse waves can be polarised. In a Young’s double-slit experiment, increasing the wavelength or slit-to-screen distance increases fringe separation, while increasing the slit separation decreases it.

偏振是横波的证据；只有横波才能偏振。在杨氏双缝实验中，增大波长或缝屏距离会增加条纹间距，而增大双缝间距则会减小条纹间距。

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5. Electricity & Circuits | 电学与电路

Current I = ΔQ/Δt, potential difference V = W/Q. Ohm’s law: V = IR at constant temperature. Resistivity ρ = RA/L. Power P = IV = I²R = V²/R. For series, R_total = R₁+R₂+…; parallel: 1/R_total = 1/R₁+1/R₂. Terminal p.d. = ε – Ir, where ε is e.m.f. and r is internal resistance. Potential dividers are widely used to produce a variable p.d.

电流I = ΔQ/Δt，电势差V = W/Q。欧姆定律：恒温下V = IR。电阻率ρ = RA/L。功率P = IV = I²R = V²/R。串联：R总 = R₁+R₂+…；并联：1/R总 = 1/R₁+1/R₂。端电压 = ε – Ir，其中ε为电动势，r为内阻。分压器广泛用于产生可调电势差。

Kirchhoff’s laws: ΣI_in = ΣI_out (junction)   ΣV = 0 round a loop

In I-V graphs, a straight line through origin indicates an ohmic conductor; a filament lamp curve shows increasing resistance with temperature. A diode only allows current in the forward direction above a threshold voltage.

在I-V图中，过原点的直线表示欧姆导体；灯丝的弯曲曲线表明电阻随温度升高而增大。二极管只允许超过阈值电压的正向电流通过。

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6. Electric Fields & Capacitors | 电场与电容器

An electric field E = F/q and points from positive to negative. For a uniform field between parallel plates: E = V/d. Coulomb’s law: F = kQ₁Q₂/r². Potential (uniform) V = Ed. Capacitance C = Q/V. For a parallel plate capacitor: C = ε₀A/d. Energy stored: ½QV = ½CV². The time constant τ = RC determines the rate of charge/discharge.

电场E = F/q，方向由正指向负。平行板间匀强电场E = V/d。库仑定律：F = kQ₁Q₂/r²。匀强电场电势：V = Ed。电容C = Q/V。平行板电容：C = ε₀A/d。储存能量：½QV = ½CV²。时间常数τ = RC决定充放电速率的快慢。

Discharge: V = V₀ e^{-\frac{t}{RC}}   Q = Q₀ e^{-\frac{t}{RC}}

The time constant is the time taken for the charge, current or p.d. to fall to 1/e (≈ 37%) of its initial value. In a parallel-plate capacitor, inserting a dielectric increases capacitance because it reduces the effective electric field.

时间常数是电荷量、电流或电势差下降到初始值1/e（≈37%）所需的时间。在平行板电容器中，插入电介质会增大电容，因为它削弱了有效电场。

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7. Magnetic Fields & Electromagnetic Induction | 磁场与电磁感应

A magnetic field exerts a force on moving charges: F = BQv sinθ. For a current-carrying conductor: F = BIL sinθ. Magnetic flux Φ = BA cosθ, and flux linkage = NΦ. Faraday’s law: induced e.m.f. = – d(NΦ)/dt. Lenz’s law gives the direction that opposes the change causing it. Transformers work on AC: Vₛ/Vₚ = Nₛ/Nₚ, and ideal efficiency assumes Pₛ = Pₚ.

磁场对运动电荷施力：F = BQv sinθ。载流导体受力：F = BIL sinθ。磁通量Φ = BA cosθ，磁通链=NΦ。法拉第定律：感生电动势= – d(NΦ)/dt。楞次定律给出抵抗引起感应变化的方向。变压器基于交流电工作：Vₛ/Vₚ = Nₛ/Nₚ，理想状态下功率相等。

Fleming’s left-hand rule predicts the direction of force on a current in a magnetic field; right-hand rule is for the induced current in a generator. When a charged particle moves perpendicular to a uniform B-field, it undergoes circular motion with radius r = mv/(BQ).

弗莱明左手定则判断磁场对电流的作用力方向；右手定则用于发电机中的感应电流方向。当带电粒子垂直射入匀强磁场时，作圆周运动，半径r = mv/(BQ)。

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8. Thermal Physics & Ideal Gases | 热物理与理想气体

Temperature is proportional to the average kinetic energy of particles. Internal energy is the sum of random kinetic and potential energies. Ideal gas equation: pV = nRT = NkT. The kinetic theory model gives pV = ⅓ N m , linking macroscopic pressure to microscopic motion. For a fixed mass, pV/T = constant.

温度与粒子的平均动能成正比。内能是随机动能和势能的总和。理想气体方程：pV = nRT = NkT。分子动理论模型给出pV = ⅓ N m ，将宏观压强与微观运动关联。对于固定质量，pV/T = 常数。

Average kinetic energy per particle: ½ m = (3/2)kT

The first law of thermodynamics states ΔU = Q + W (work done on the system). For an isothermal process, ΔU = 0, so Q = -W. In an adiabatic process, Q = 0, so ΔU = W. When a gas expands against an external pressure, it does work and its internal energy may decrease.

热力学第一定律表述为ΔU = Q + W（对系统做功）。等温过程中ΔU = 0，所以Q = -W。绝热过程中Q = 0，所以ΔU = W。当气体对外界做功膨胀时，内能可能减少。

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9. Quantum Physics & Nuclear Physics | 量子物理与核物理

Photons have energy E = hf. The photoelectric effect demonstrates particle behaviour: hf = Φ + K_max, where Φ is work function. Threshold frequency f₀ = Φ/h. Electrons in atoms occupy discrete energy levels; emission/absorption lines correspond to transitions. Wave–particle duality: λ = h/p (de

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