📚 Year 7 CIE Physics: Core Knowledge Summary | Year 7 CIE 物理：核心知识点梳理
Welcome to your essential summary of Year 7 CIE Physics! This guide covers the core topics you need to master: forces and motion, energy, electricity, waves (light and sound), the particle model of matter, Earth and space, and key measurement skills. Each section presents clear explanations with paired English and Chinese passages to support bilingual learning. Let's revise the foundations that will help you excel in Checkpoint and beyond.
欢迎来到 Year 7 CIE 物理核心知识点梳理！本指南涵盖你需要掌握的重要主题：力与运动、能量、电学、波（光和声音）、物质的粒子模型、地球与太空以及关键的测量技能。每个部分都提供清晰的中英文对照解释，支持双语学习。让我们复习这些基础，助力你在 Checkpoint 及后续学习中取得优异成绩。
1. Forces and Motion | 力与运动
A force is a push or a pull that can change an object's speed, direction of motion, or shape. The SI unit of force is the newton (N).
力是推或拉，能改变物体的速度、运动方向或形状。力的国际单位是牛顿 (N)。
Forces can be contact forces, such as friction and air resistance, or non‑contact forces, such as gravity and magnetic force. Gravity is the force of attraction between any two masses.
力可分为接触力（如摩擦力、空气阻力）和非接触力（如重力、磁力）。重力是任意两个质量之间的吸引力。
Mass is the amount of matter in an object, measured in kilograms (kg). Weight is the force of gravity acting on the mass, measured in newtons (N). The relationship is:
质量是物体所含物质的多少，单位为千克 (kg)。重量是作用在质量上的重力，单位为牛顿 (N)。两者关系为：
weight = mass × gravitational field strength (g)
重量 = 质量 × 重力场强度 (g)
On Earth, g ≈ 10 N/kg. A 5 kg object therefore has a weight of about 50 N.
在地球上，g ≈ 10 N/kg。因此一个 5 kg 的物体其重量约为 50 N。
When forces on an object are balanced, the object remains at rest or moves at a constant speed. Unbalanced forces cause acceleration, deceleration, or a change in direction.
当作用在物体上的力平衡时，物体保持静止或匀速运动。不平衡的力会导致加速、减速或方向改变。
Friction is a force that opposes motion. It can be useful (e.g. walking, braking) or a nuisance (e.g. wearing out machine parts). Lubricants and streamlining reduce unwanted friction.
摩擦力是阻碍运动的力。它可能是有益的（如行走、刹车），也可能有害（如磨损机器部件）。润滑剂和流线型设计可以减少不必要的摩擦。
Speed describes how fast something moves. It is calculated using the formula:
速度描述物体运动的快慢。计算公式为：
speed = distance / time
速度 = 路程 / 时间
Common units are metres per second (m/s) or kilometres per hour (km/h). A distance‑time graph shows motion: a horizontal line means stationary, a sloping straight line means constant speed, and a steeper slope indicates a higher speed.
常用单位是米每秒 (m/s) 或千米每小时 (km/h)。距离‑时间图显示运动状态：水平线表示静止，倾斜直线表示匀速，斜率越大速度越高。
2. Energy | 能量
Energy is the ability to do work. It is measured in joules (J). Energy exists in many forms: kinetic (movement), gravitational potential (height), elastic potential (stretched or compressed), thermal (heat), chemical (stored in fuels and food), electrical, light, and sound.
能量是做功的能力，单位为焦耳 (J)。能量有多种形式：动能（运动）、重力势能（高度）、弹性势能（拉伸或压缩）、热能（热）、化学能（储存在燃料和食物中）、电能、光能和声能。
The law of conservation of energy states that energy cannot be created or destroyed, only transferred from one form to another.
能量守恒定律指出，能量既不会凭空产生也不会凭空消失，只能从一种形式转换成另一种形式。
ergy + thermal energy. When a ball falls, gravitational potential energy → kinetic energy.
在灯泡中，电能 → 光能 + 热能。球下落时，重力势能 → 动能。
Energy resources are classified as renewable (e.g. solar, wind, hydroelectric, geothermal) or non‑renewable (e.g. fossil fuels, nuclear). Using renewables helps conserve finite resources and reduces pollution.
能源分为可再生能源（如太阳能、风能、水力发电、地热能）和非可再生能源（如化石燃料、核能）。使用可再生能源有助于节约有限资源并减少污染。
3. Electricity | 电学
A simple circuit must have a complete path, a source of electrical energy (cell or battery), and a load (e.g. a bulb or buzzer). Circuit diagrams use standard symbols: a cell is shown by a long and a short parallel line, a bulb by a circle with a cross, and a resistor by a zigzag line.
简单电路必须有完整的回路、电源（电池）和用电器（如灯泡或蜂鸣器）。电路图使用标准符号：电池用一长一短平行线表示，灯泡用带叉的圆表示，电阻器用锯齿线表示。
Current is the flow of electric charges around a circuit and is measured in amperes (A) using an ammeter connected in series.
电流是电荷在电路中的流动，单位为安培 (A)，用串联在电路中的电流表来测量。
In a series circuit, all components are connected one after another. The current is the same everywhere, but the voltage is shared. If one bulb breaks, the circuit is broken and all bulbs go out.
在串联电路中，所有元件依次连接。电流处处相等，但电压被分配。若一个灯泡损坏，电路断开，所有灯泡熄灭。
In a parallel circuit, each component is on its own separate branch. The voltage across each branch is the same, and the total current equals the sum of the currents in the branches. If one bulb fails, the others remain on.
在并联电路中，每个元件位于各自的支路上。各支路电压相等，总电流等于各支路电流之和。若一个灯泡损坏，其他灯泡仍亮着。
| Feature 特征 | Series Circuit 串联电路 | Parallel Circuit 并联电路 |
|---|---|---|
| Current 电流 | Same everywhere 各处相等 | Splits across branches 各支路分配 |
| Voltage 电压 | Shared across components 元件间分配 | Same across each branch 各支路相等 |
| Failure of one bulb 一灯泡损坏 | All bulbs go out 全部熄灭 | Other bulbs stay on 其他灯泡亮着 |
Conductors, such as metals and graphite, allow electric current to flow easily. Insulators, such as rubber and plastic, do not. Conductors are used for wires; insulators are used as safety coatings.
导体（如金属和石墨）允许电流轻易通过；绝缘体（如橡胶和塑料）则不能。导体用于制作导线，绝缘体用作安全包层。
4. Light | 光
Light travels in straight lines. When an opaque object blocks light, a shadow is formed. The size and shape of a shadow depend on the object's distance from the light source and the angle of the light.
光沿直线传播。不透明物体挡住光时会形成影子。影子的形状和大小取决于物体与光源的距离以及光的角度。
The law of reflection states that the angle of incidence equals the angle of reflection, measured from the normal (a line perpendicular to the surface).
反射定律指出，入射角等于反射角，均从法线（垂直于表面的线）量起。
An image in a plane (flat) mirror is upright, the same size as the object, laterally inverted (left and right are swapped), and virtual. The image distance behind the mirror equals the object distance in front of it.
平面镜形成的像是正立的、与物等大、左右颠倒的虚像。像到镜面的距离等于物到镜面的距离。
Refraction occurs when light passes from one medium to another at an angle. For example, when light enters glass from air, it bends towards the normal because glass is more dense optically.
光从一种介质斜射入另一种介质时会发生折射。例如，光从空气进入玻璃时，会向法线偏折，因为玻璃的光密性更高。
White light can be split into the colours of the spectrum (red, orange, yellow, green, blue, indigo, violet) by a prism – this is called dispersion. A rainbow is a natural example of dispersion through water droplets.
白光通过棱镜可被分解为光谱色（红、橙、黄、绿、蓝、靛、紫）——这称为色散。彩虹就是阳光通过水滴色散的天然例子。
An opaque object appears the colour it reflects; all other colours are absorbed. A red apple reflects red light and absorbs other colours. A transparent object allows light of its own colour to pass through and absorbs the rest.
不透明物体呈现它所反射的颜色，吸收其他色光。红苹果反射红光，吸收其他色光。透明物体允许与其相同颜色的光透过，吸收其余色光。
5. Sound | 声音
Sound is produced by vibrations. A vibrating object makes the surrounding medium (solid, liquid or gas) vibrate, creating a sound wave that travels to our ears.
声音由振动产生。振动着的物体使周围的介质（固体、液体或气体）随之振动，形成声波传到我们耳中。
Sound needs a medium to travel; it cannot travel through a vacuum. Sound travels fastest in solids, slower in liquids, and slowest in gases because particles are closer together in solids, transferring vibrations more quickly.
声音需要介质才能传播，不能在真空中传播。声音在固体中传播最快，液体中次之，气体中最慢，因为固体粒子排列最紧密，能更快地传递振动。
The pitch of a sound depends on its frequency – how many vibrations per second (hertz, Hz). A high frequency gives a high‑pitched sound. The loudness depends on the amplitude of the vibration; a larger amplitude gives a louder sound.
音调的高低取决于频率，即每秒振动次数（赫兹，Hz）。频率高则音调高。响度取决于振动的振幅；振幅越大声音越响。
Humans can hear sounds in the frequency range from approximately 20 Hz to 20 000 Hz. Sounds with frequencies above 20 000 Hz are called ultrasound. Ultrasound is used for medical scanning and by some animals, like bats, for navigation.
人类能听到约 20 Hz 至 20 000 Hz 的声音。频率超过 20 000 Hz 的声音称为超声波。超声波用于医学扫描，蝙蝠等动物则用来导航。
6. Matter and Materials | 物质与材料
Matter exists in three main states: solid, liquid and gas. In solids, particles are tightly packed in a regular pattern and vibrate in fixed positions. In liquids, particles are close together but can slide past each other, allowing the liquid to flow. In gases, particles are far apart and move rapidly in all directions.
物质主要以三种状态存在：固态、液态和气态。固态时粒子紧密排列成规则形状并在固定位置振动；液态时粒子仍比较密集但可彼此滑动，使液体流动；气态时粒子相隔很远并快速向各个方向运动。
uid), and sublimation (solid → gas directly). These changes occur at specific temperatures – melting point and boiling point.
物态变化包括熔化（固→液）、凝固（液→固）、沸腾/蒸发（液→气）、凝结（气→液）和升华（固→气）。这些变化发生在特定温度——熔点和沸点。
Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration. It happens in liquids and gases and is evidence of the particle model.
扩散是粒子从高浓度区域向低浓度区域的运动，发生在液体和气体中，是粒子模型的有力证据。
Density measures how much mass is packed into a given volume.
密度衡量单位体积内所含质量的多少。
density = mass / volume
密度 = 质量 / 体积
Units are g/cm³ or kg/m³. Solids are usually denser than liquids and gases because their particles are more tightly packed.
单位为 g/cm³ 或 kg/m³。固体通常比液体和气体密度大，因为其粒子排列更紧密。
7. Earth and Space | 地球与太空
Our solar system consists of the Sun and the eight planets in order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. My Very Easy Method Just Speeds Up Naming is a common mnemonic.
太阳系由太阳和八大行星组成，排列顺序为：水星、金星、地球、火星、木星、土星、天王星、海王星。
Earth rotates on its axis once every 24 hours, causing day and night. The side facing the Sun experiences daytime; the opposite side experiences nighttime.
地球绕地轴自转一周约 24 小时，产生昼夜交替。面向太阳的一侧是白昼，背对太阳的一侧是黑夜。
Earth revolves around the Sun in approximately 365¼ days, leading to a year and, together with the tilt of Earth's axis, causing the seasons. When the Northern Hemisphere is tilted towards the Sun, it is summer there and winter in the Southern Hemisphere.
地球绕太阳公转一周约 365¼
Published by TutorHao | Year 7 Physics Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图