📚 Core Knowledge Summary for Year 11 AQA Physics | AQA 物理核心知识点梳理
This article provides a concise yet comprehensive summary of the key topics covered in Year 11 AQA GCSE Physics (and Combined Science: Trilogy Physics). From energy stores to space physics, each section highlights the essential concepts, equations, and real-world applications to help you revise effectively for your exams.
本文为Year 11 AQA GCSE物理（及综合科学：三部曲物理）的核心知识点提供一个简洁而全面的梳理。从能量储存到空间物理，每个部分都突出了关键概念、方程和实际应用，帮助你高效备考。
1. Energy Stores and Transfers | 能量储存与转移
Energy can be stored in various forms: kinetic, gravitational potential, elastic potential, thermal, chemical, nuclear, magnetic and electrostatic. Energy is transferred between stores by mechanical work, electrical work, heating or radiation. The law of conservation of energy states that energy cannot be created or destroyed; it can only be transferred, stored or dissipated (spread out to the surroundings as thermal energy). In all real processes, some energy ends up in less useful thermal stores, which is why efficiency is always less than 1.
能量可以储存为多种形式：动能、重力势能、弹性势能、热能、化学能、核能、磁能和静电能。能量通过机械做功、电流做功、加热或辐射在储存库之间转移。能量守恒定律指出，能量不能被创造或消灭，只能被转移、储存或耗散（以热能形式散逸到环境中）。在所有实际过程中，一部分能量总是转移到不太有用的热能储存库，因此效率总是小于1。
The kinetic energy of a moving object depends on its mass and speed:
Eₖ = ½ m v²
运动物体的动能取决于其质量和速度：
Eₖ = ½ m v²
Gravitational potential energy gained by an object raised through height h is:
Eₚ = m g h (g = 9.8 N/kg on Earth)
物体被举高h所增加的重力势能为：
Eₚ = m g h (g = 9.8 N/kg在地球表面)
ant (N/m) and e is the extension (m). Understanding these energy stores allows you to calculate the speed of a falling object or the height a projectile can reach by assuming no energy is lost.
对于被拉伸或压缩的弹簧，弹性势能由Eₑ = ½ k e²给出，其中k是弹簧常数（N/m），e是伸长量（m）。理解这些能量储存库后，你可以通过假设无能量损失来计算下落物体的速度或抛射物体能达到的高度。
2. Specific Heat Capacity and Latent Heat | 比热容与潜热
The specific heat capacity (c) of a material is the energy required to raise the temperature of 1 kg of the substance by 1 °C. The energy change ΔE (J) is calculated by:
ΔE = m c Δθ
材料的比热容(c)是使1 kg该物质温度升高1 °C所需的能量。能量变化ΔE（焦耳）由下式计算：
ΔE = m c Δθ
Latent heat is the energy absorbed or released during a change of state without a change in temperature. Specific latent heat of fusion (Lf) applies to melting/freezing, and specific latent heat of vaporisation (Lv) applies to boiling/condensing:
ΔE = m L
潜热是物质在温度不变时发生状态变化所吸收或释放的能量。熔化比潜热(Lf)适用于熔化/凝固，汽化比潜热(Lv)适用于沸腾/凝结：
ΔE = m L
When heating a substance, a flat section on a temperature–time graph indicates a change of state, where the energy supplied is used to break bonds rather than raise the temperature. Water has an unusually high specific heat capacity, which makes it effective for thermal energy storage and for moderating the Earth's climate.
在加热物质时，温度-时间图上的水平段表示状态变化，此时提供的能量用于打破分子间键而不是升高温度。水具有异常高的比热容，这使其在热能储存和调节地球气候方面非常有效。
3. Electric Circuits and Ohm's Law | 电路与欧姆定律
nsferred per unit charge: V = W / Q, in volts (V). Resistance (R) is defined as V / I and is measured in ohms (Ω).
电流(I)是电荷流动的速率：I = Q / t，单位为安培(A)。组件两端的电势差(V)是每单位电荷转移的能量：V = W / Q，单位为伏特(V)。电阻(R)定义为V / I，单位为欧姆(Ω)。
Ohm' , so resistance remains constant. In a series circuit, the current is the same everywhere, the total resistance is the sum of individual resistances (Rtotal = R₁ + R₂ + ...), and the supply voltage is shared. In a parallel circuit, the potential difference across each branch is the same, the total current is the sum of the branch currents, and the total resistance is less than the smallest individual resistance.
欧姆定律指出，在恒定温度下，通过欧姆导体的电流与其两端的电势差成正比，因此电阻保持不变。在串联电路中，各处电流相等，总电阻等于各电阻之和（R总 = R₁ + R₂ + ...），电源电压被分配。在并联电路中，各支路电势差相等，总电流等于各支路电流之和，总电阻小于最小的单个电阻。
Common components like diodes, filament lamps and thermistors display non-ohmic behaviour. The resistance of a thermistor decreases as temperature rises, while the resistance of an LDR (light-dependent resistor) decreases as light intensity increases.
常见元件如二极管、白炽灯和热敏电阻表现出非欧姆特性。热敏电阻的阻值随温度升高而减小，而光敏电阻(LDR)的阻值随光照强度增加而减小。
4. Electrical Power, Energy and Household Safety | 电功率、电能与家庭用电安全
Electrical power (P) is the rate of energy transfer. It can be calculated by:
P = I V, P = I² R, P = V² / R
电功率(P)是能量转换的速率。可以通过以下公式计算：
P = I V, P = I² R, P = V² / R
omestic electricity bills, the unit is the kilowatt-hour (kWh), where 1 kWh = 3.6 × 10⁶ J.
在给定时间(t)内传递的能量(E)为E = P t，单位为焦耳(J)。家庭电费单中使用的单位是千瓦时(kWh)，1 kWh = 3.6 × 10⁶ J。
In the UK, mains electricity is alternating current (a.c.) at 50 Hz with a voltage of about 230 V. Safety features include fuses, circuit breakers and earthing. A fuse melts if too much current flows, breaking the circuit. Earthing provides a low-resistance path to the ground, causing a large current that blows the fuse if a live wire touches a metal casing. Double insulation eliminates the need for an earth wire.
在英国，市电是频率为50 Hz的交流电(a.c.)，电压约为230 V。安全装置包括保险丝、断路器和接地线。如果电流过大，保险丝会熔断以断开电路。接地提供一条低电阻路径到大地，若火线碰到金属外壳，会产生大电流使保险丝熔断。双重绝缘则无需接地线。
5. Particle Model and Density | 粒子模型与密度
The particle model helps explain the properties of solids, liquids and gases. In solids, particles are closely packed in a regular arrangement and vibrate in fixed positions. Liquids have particles that are close together but can move past each other. In gases, particles are far apart and move randomly at high speeds. Changes of state can be explained in terms of energy changes altering the arrangement and motion of particles.
粒子模型有助于解释固体、液体和气体的性质。固体中，粒子紧密排列成规则结构并在固定位置振动。液体的粒子相互接近但可以彼此滑动。气体中，粒子相距很远并以高速随机运动。状态变化可以通过能量改变粒子的排列和运动来解释。
Density (ρ) is mass per unit volume:
ρ = m / V
密度(ρ)是单位体积的质量：
ρ = m / V
Internal energy is the sum of the kinetic energy and potential energy of the particles in a system. Heating increases the kinetic energy of particles and raises temperature; during a change of state, the potential energy changes while the temperature remains constant. The density of a material can be determined experimentally using a balance and a ruler (for regular solids) or a displacement method (for irregular objects and liquids).
内能是系统内粒子的动能与势能之和。加热会增加粒子的动能并升高温度；在状态变化期间，势能发生变化而温度保持恒定。材料的密度可以通过天平和直尺（规则固体）或排水法（不规则物体和液体）实验测定。
6. Radioactive Decay and Half-life | 放射性衰变与半衰期
Atoms have a small central nucleus containing protons and neutrons, surrounded by electrons. Isotopes of an element have the same number of protons but different numbers of neutrons. Some isotopes are unstable and undergo radioactive decay to become more stable, emitting alpha (α), beta (β) or gamma (γ) radiation. Alpha particles are helium nuclei, beta particles are fast-moving electrons, and gamma rays are electromagnetic waves.
原子有一个微小的中心原子核，包含质子和中子，核外有电子环绕。元素的同位素质子数相同但中子数不同。一些同位素不稳定并发生放射性衰变以变得更稳定，放出α（阿尔法）、β（贝塔）或γ（伽马）辐射。α粒子是氦核，β粒子是高速电子，γ射线是电磁波。
Radioactive decay is a random process, meaning it is impossible to predict exactly when a particular nucleus will decay. The half-life is the time taken for half the radioactive nuclei in a sample to decay, or for the count rate to fall to half its initial value. It can be determined from a decay graph. Activity is the rate of decay and is measured in becquerels (Bq).
放射性衰变是随机过程，无法精确预测某个原子核何时衰变。半衰期是样本中一半放射性原子核发生衰变所需的时间，或计数率降至初始值一半所需的时间。它可以从衰变曲线图中确定。活度是衰变的速率，单位是贝克勒尔(Bq)。
Nuclear equations can be written to show decay. For example, alpha decay of uranium-238:
²³⁸U → ²³⁴Th + ⁴He
核方程可以表示衰变。例如，铀-238的α衰变：
²³⁸U → ²³⁴Th + ⁴He
Contamination and irradiation present different hazards. Irradiation is exposure to radiation, whereas contamination occurs when radioactive material gets onto or into an object. Safety precautions include reducing exposure time, increasing distance and using shielding.
污染和辐照具有不同的危害。辐照是暴露于辐射之下，而污染是指放射性物质沾染或进入物体。安全预防措施包括减少照射时间、加大距离和使用屏蔽。
7. Forces, Motion and Newton's Laws | 力、运动与牛顿定律
contact force, friction, tension and upthrust. A resultant force causes an object to accelerate according to Newton's second law:
F = m a
力是既有大小又有方向的矢量。常见的力包括重力(W = m g)、法向接触力、摩擦力、张力和上推力。合力使物体产生加速度，符合牛顿第二定律：
F = m a
For motion in a straight line with constant acceleration, the SUVAT equations are used:
v = u + a t, s = u t + ½ a t², v² = u² + 2 a s
物体沿直线做匀加速运动时，使用SUVAT方程组：
v = u + a t, s = u t + ½ a t², v² = u² + 2 a s
Newton's first law states that an object remains at rest or at constant velocity unless acted upon by a resultant force. Newton's third law states that when two objects interact, they exert equal and opposite forces on each other. Free-body diagrams and vector diagrams can be used to find resultant forces.
牛顿第一定律指出，物体将保持静止或匀速直线运动状态，除非受到合外力的作用。牛顿第三定律指出，当两个物体相互作用时，它们彼此施加大小相等、方向相反的力。受力图和矢量图可用于求合力。
8. Momentum and Safety | 动量与安全
Momentum (p) is a vector quantity defined as the product of mass and velocity:
p = m v
动量(p)是矢量，其定义为质量与速度的乘积：
p = m v
In a closed system, the total momentum before an event is equal to the total momentum after the event – this is the conservation of momentum. The force acting on an object is equal to the rate of change of momentum:
F = Δp / Δt (from F = m a)
在一个封闭系统中，事件前后的总动量相等——这就是动量守恒。作用在物体上的力等于动量的变化率：
F = Δp / Δt (由 F = m a 推导)
hange occurs (since F = Δp/Δt). This reduces the risk of injury in collisions. Momentum calculations are essential for understanding collisions and explosions.
安全气囊、溃缩区和安全带等安全装置通过延长动量变化发生的时间来减小作用在乘客身上的力（因为F = Δp/Δt）。这降低了碰撞中的受伤风险。动量计算对于理解碰撞和爆炸至关重要。
9. Wave Properties and the Wave Equation | 波的特性与波动方程
Waves transfer energy from one place to another without transferring matter. In transverse waves, the oscillations are perpendicular to the direction of energy transfer (e.g. water waves, S-waves, all electromagnetic waves). In longitudinal waves, the oscillations are parallel to the direction of energy transfer (e.g. sound waves, P-waves).
波将能量从一处传递到另一处而不传递物质。在横波中，振动方向与能量传递方向垂直（如水波、S波、所有电磁波）。在纵波中，振动方向与能量传递方向平行（如声波、P波）。
Key wave quantities: amplitude – the maximum displacement from the rest position; wavelength (λ) – the distance between successive corresponding points; frequency (f) – the number of complete waves passing a point per second (Hz); period (T) – the time for one complete wave: f = 1 / T. The wave speed (v) equation is:
v = f λ
关键的波的物理量：振幅——离开平衡位置的最大位移；波长(λ)——相邻对应点之间的距离；频率(f)——每秒通过某点的完整波数（Hz）；周期(T)——一个完整波所需的时间：f = 1 / T。波速(v)公式为：
v = f λ
Waves undergo reflection, refraction and diffraction. Refraction occurs when a wave crosses a boundary between media and changes speed, causing a change in direction unless the wave hits normal. Diffraction is the spreading out of waves when they pass through a gap or around an obstacle; the effect is greatest when the gap size is similar to the wavelength.
波会发生反射、折射和衍射。折射发生在波越过介质边界且波速改变时，除非波垂直入射，否则会导致方向改变。衍射是波通过缝隙或绕过障碍物时向外扩散的现象；当缝隙大小与波长相当时，衍射效应最显著。
10. Electromagnetic Spectrum and Uses | 电磁波谱及其应用
/s in a vacuum. The spectrum, in order of increasing frequency and decreasing wavelength, is: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays. All EM waves can be reflected, refracted and diffracted.
电磁波是横波，在真空中以3.0 × 10⁸ m/s 的速度传播。电磁波谱按频率递增、波长递减的顺序排列为：无线电波、微波、红外线、可见光、紫外线、X射线和伽马射线。所有电磁波都可以被反射、折射和衍射。
Different parts of the spectrum have different properties and uses: radio waves – broadcasting and
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