📚 Core Concepts of Year 7 CIE Physics | Year 7 CIE 物理：核心知识点梳理
Year 7 CIE Physics introduces students to the fundamental principles that govern the physical world. From understanding forces and energy to exploring electricity, magnetism, waves, and the solar system, this course builds a strong foundation for scientific thinking. This article summarises the core concepts with clear explanations in both English and Chinese, helping students review effectively and prepare for assessments.
七年级 CIE 物理课程引领学生探索支配物质世界的基本原理。从力和能量到电、磁、波和太阳系，这门课程为科学思维奠定坚实基础。本文用清晰的中英双语梳理核心知识点，助力学生高效复习并做好考试准备。
1. Introduction to Physics and Measurement | 物理学入门与测量
Physics is the study of matter, energy, and the interactions between them. It seeks to explain how things move, why objects fall, and what light and sound really are. Understanding physics helps us make sense of the world, from the tiniest particles to the vastness of space.
物理学是研究物质、能量及其相互作用的学科。它试图解释物体如何运动、为何下落，以及光和声音的本质是什么。理解物理能帮助我们认识世界，从最小的粒子到浩瀚的宇宙。
In physics, measurement is essential. We use standard units called SI units. The most common base units in Year 7 are the metre (m) for length, the kilogram (kg) for mass, and the second (s) for time. Accurate measurements often involve tools such as rulers, stopwatches, and balances.
在物理中，测量至关重要。我们使用被称为国际单位制的标准单位。七年级最常见的基准单位有：长度用米（m），质量用千克（kg），时间用秒（s）。精确测量通常需要用到尺子、秒表和天平等工具。
Every measurement has some uncertainty. We repeat readings and calculate an average to improve reliability. Significant figures and decimal places help us express results to an appropriate level of precision, but at this stage the focus is on careful observation and recording data in tables.
任何测量都存在一定的不确定性。我们通过重复读数并计算平均值来提高可靠性。有效数字和小数位有助于我们以适当的精度表示结果，但在这一阶段，重点是仔细观察并将数据记录在表格中。
2. Forces and Motion | 力与运动
A force is a push or a pull that can change an object's speed, direction, or shape. Forces are measured in newtons (N). Some forces require contact, like friction, air resistance, and tension. Others, such as gravity, magnetism, and electrostatic force, act at a distance.
力是能够改变物体速度、方向或形状的推或拉。力的单位是牛顿（N）。有些力需要接触，如摩擦力、空气阻力和张力；而其他力如重力、磁力和静电力则可以在一定距离外产生作用。
Gravity is a non‑contact force that pulls objects towards the centre of the Earth. The weight of an object is the force of gravity on its mass and can be calculated using the equation: W = m g pposes motion and can be useful (e.g., walking, braking) or unwanted (e.g., wearing out machinery).
重力是一种非接触力，将所有物体拉向地心。物体的重量是重力对其质量的作用力，可以通过公式 W = m g 计算，其中地球上的 g 约为 10 N/kg。摩擦力阻碍运动，既有益处（如行走、刹车），也有弊端（如磨损机械）。
When forces on an object are balanced, it remains at rest or moves at constant speed. Unbalanced forces cause acceleration or deceleration. The speed of an object is the distance travelled per unit time:
v = s / t
where v is speed, s is distance and t is time. Distance‑time graphs show how far an object has moved; a steeper slope means a higher speed.
当物体所受的力平衡时，它将保持静止或匀速运动。不平衡力则会导致加速或减速。物体的速度是单位时间内通过的距离：
v = s / t
其中 v 表示速度，s 表示距离，t 表示时间。距离‑时间图显示物体的移动距离，斜率越大代表速度越快。
3. Magnetism | 磁性
Magnets have two poles – north (N) and south (S). Like poles repel each other, while unlike poles attract. The region around a magnet where it can exert a force is called its magnetic field, represented by field lines that run from the north pole to the south pole outside the magnet.
磁铁有两个磁极——北极（N）和南极（S）。同名磁极相互排斥，异名磁极相互吸引。磁铁周围能产生力的区域称为磁场，用磁感线表示，在磁铁外部从北极指向南极。
The Earth itself behaves like a giant magnet, with its magnetic south pole near the geographic north pole. A compass needle is a small magnet that aligns with Earth's magnetic field, pointing approximately north. This phenomenon is essential for navigation.
地球本身就像一块巨大的磁铁，其地磁南极位于地理北极附近。指南针的指针是一个小磁铁，会与地球磁场对齐，大致指向北方。这一现象对导航至关重要。
Electromagnetism is introduced in Year 7 through simple electromagnets – a coil of wire wrapped around an iron core that becomes magnetic when electric current flows. Electromagnets can be switched on and off and are used in cranes, doorbells, and speakers.
电磁现象在七年级通过简单的电磁铁引入——缠绕在铁芯上的线圈，通电后会产生磁性。电磁铁可以通断，广泛应用于起重机、门铃和扬声器中。
4. Energy | 能量
Energy is the ability to do work. It exists in many forms: kinetic (movement), gravitational potential (height), elastic potential (stretched or compressed materials), thermal (heat), chemical (food and fuels), electrical, light, and sound. Energy is measured in joules (J).
能量是做功的能力。它以多种形式存在：动能（运动）、重力势能（高度）、弹性势能（拉伸或压缩的材料）、热能（热）、化学能（食物和燃料）、电能、光能和声能。能量的单位是焦耳（J）。
The principle of conservation of energy states that energy cannot be created or destroyed, only transferred or transformed from one form to another. For example, when a ball is dropped, gravitational potential energy changes into kinetic energy.
能量守恒定律指出，能量既不能被创造也不能被消灭，只能从一种形式转移或转化为另一种形式。例如，球下落时，重力势能转化为动能。
Energy resources are classified as renewable (solar, wind, tidal, hydroelectric, geothermal) or non‑renewable (coal, oil, natural gas). Using renewable resources helps reduce pollution and combat climate change.
能源分为可再生（太阳能、风能、潮汐能、水能、地热能）和不可再生（煤、石油、天然气）。使用可再生能源有助于减少污染，应对气候变化。
5. Basics of Electricity | 电学基础
An electric circuit is a complete loop that allows current to flow. The essential components include a cell or battery (power source), wires (conductors), a switch, and a load such as a lamp or resistor. Standard symbols are used to draw circuit diagrams.
电路是允许电流流动的完整回路。基本元件包括电池（电源）、导线（导体）、开关以及灯泡或电阻等负载。绘制电路图时使用标准符号。
Electric current is the flow of electric charge and is measured in amperes (A). Voltage (potential difference), measured in volts (V), provides the 'push' that drives the current. Resistance, measured in ohms (Ω), restricts the flow of current. A simple relationship is often expressed as:
V = I R
电流是电荷的流动，以安培（A）为单位。电压（电势差）以伏特（V）为单位，提供驱动电流的“推力”。电阻以欧姆（Ω）为单位，限制电流流动。简单关系通常表示为：
V = I R
Circuits can be connected in series or parallel. In a series circuit, the current is the same everywhere, and the total voltage is shared. In a parallel circuit, the current splits but the voltage across each branch is the same. Understanding these arrangements helps in designing safe and efficient electrical systems.
电路可以串联或并联。串联电路中，各处电流相等，总电压被分配；并联电路中，电流分流，但各支路电压相同。理解这些连接方式有助于设计安全高效的电路系统。
6. Particle Model and Density | 粒子模型与密度
All matter is made of tiny particles. The particle model explains the three states of matter: solids have particles packed closely in a fixed arrangement, vibrating in place; liquids have particles close together but able to move past each other; gases have particles far apart moving randomly at high speed.
所有物质均由微小粒子构成。粒子模型解释物质的三种状态：固态粒子紧密排列在固定位置，只在原地振动；液态粒子相距较近，但能相互滑动；气态粒子相距很远，高速无规则运动。
Density describes how much mass is packed into a given volume. It is calculated using the formula:
ρ = m / V
where ρ is density, m is mass and V is volume. Objects with a density less than water (1 g/cm³) float, while denser objects sink.
密度描述单位体积内所含质量的多少，用公式计算：
ρ = m / V
其中 ρ 为密度，m 为质量，V 为体积。密度小于水（1 g/cm³）的物体上浮，密度大的物体则下沉。
Changes of state, such as melting, freezing, boiling, and condensation, occur when energy is added or removed. During a change of state, the temperature remains constant even though energy is being transferred – this is a key concept linked to latent heat at higher levels.
物态变化，如熔化、凝固、沸腾和凝结，是在能量增加或减少时发生的。在物态变化过程中，即使能量在传递，温度也保持恒定——这是与更高年级潜热相关的核心概念。
7. Heat Transfer | 热传递
Heat energy can be transferred by conduction, convection, and radiation. Conduction occurs mainly in solids, where vibrating particles pass energy to neighbouring particles. Metals are good conductors; non‑metals like plastic and wood are insulators.
热能可以通过传导、对流和辐射进行传递。传导主要发生在固体中，振动的粒子将能量传递给相邻粒子。金属是良导体，塑料和木材等非金属是绝缘体。
Convection happens in liquids and gases. When a fluid is heated, it expands, becomes less dense, and rises. Cooler, denser fluid sinks, creating a convection current. This is how water boils in a kettle and how sea breezes form.
对流发生在液体和气体中。流体受热后膨胀、密度减小并上升，较冷、密度较大的流体下沉，形成对流循环。这就是水壶烧水以及海风形成的原理。
Infrared radiation can travel through a vacuum, which is how the Sun's energy reaches the Earth. Dark, matt surfaces are good emitters and absorbers of radiation, while light, shiny surfaces reflect more radiation and are poor absorbers. Practical examples include solar panels, flasks, and cooking appliances.
红外辐射可以在真空中传播，这正是太阳能量到达地球的方式。暗色粗糙表面是良好的辐射发射体和吸收体，而光亮表面反射辐射较多，吸收较差。实际应用包括太阳能电池板、保温瓶和烹饪器具。
8. Sound | 声音
Sound is produced by vibrations. When an object vibrates, it displaces particles in the surrounding medium (usually air), creating compressions and rarefactions that travel as a longitudinal wave. Sound cannot travel through a vacuum because there are no particles to vibrate.
声音由振动产生。物体振动时，会使周围介质（通常是空气）中的粒子发生位移，形成疏密相间的纵向波。声音不能在真空中传播，因为没有可振动的粒子。
The pitch of a sound depends on its frequency – measured in hertz (Hz). Higher frequency vibrations produce a higher pitch. Loudness is related to the amplitude of the wave; a larger amplitude gives a louder sound. Humans can hear frequencies from roughly 20 Hz to 20 000 Hz.
音调的高低取决于频率，单位是赫兹（Hz）。频率越高，音调越高。响度与波的振幅有关，振幅越大，声音越响。人类可听到的频率范围大约在 20 Hz 到 20 000 Hz 之间。
Sound waves can reflect off surfaces, causing echoes. The time between the original sound and the echo can be used to calculate distances, a principle employed in sonar and medical ultrasound. Ultrasound refers to frequencies above human hearing and has many diagnostic and industrial uses.
声波遇到物体会反射，产生回声。原始声音与回声之间的时间差可用于计算距离，这一原理被应用于声呐和医用超声波。超声波指超出人耳听觉范围的频率，在诊断和工业上有多种用途。
9. Light | 光
lines at a speed of approximately 3.0 × 10⁸ m/s in a vacuum. We represent light using rays – s form when an opaque object blocks light, providing evidence for rectilinear propagation.
光是一种能量形式，在真空中以约 3.0 × 10⁸ 米/秒的速度沿直线传播。我们用光线（带箭头的直线）表示光的传播方向。不透光物体挡住光线时会形成影子，这证明了光的直线传播。
When light hits a smooth surface, it obeys the law of reflection: the angle of incidence equals the angle of reflection, both measured from the normal. Refraction occurs when light passes from one transparent medium to another, changing speed and direction, which is why a straw appears bent in water.
光照射到光滑表面时遵循反射定律：入射角等于反射角，均从法线开始测量。当光从一种透明介质进入另一种介质时会发生折射，改变速度和方向，这就是吸管在水中看起来弯曲的原因。
White light is a mixture of all colours. A prism can split white light into a spectrum (dispersion) – red, orange, yellow, green, blue, indigo, violet. The colour of an object depends on which wavelengths of light it reflects or transmits. A red apple reflects red light and absorbs other colours.
白光是由所有颜色混合而成的。棱镜可以将白光分解成光谱（色散）——红、橙、黄、绿、蓝、靛、紫。物体的颜色取决于它反射或透射哪些波长的光。红苹果反射红光，吸收其他颜色。
10. The Solar System and Beyond | 太阳系与宇宙
Our solar system consists of the Sun, eight planets, dwarf planets, moons, asteroids, and comets. The planets in order from the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. The Sun, a star, provides almost all the energy for Earth.
我们的太阳系由太阳、八颗行星、矮行星、卫星、小行星和彗星组成。按照离太阳从近到远的顺序，行星依次是水星、金星、地球、火星、木星、土星、天王星和海王星。太阳是一颗恒星，为地球提供几乎全部的能量。
The Earth rotates on its axis once every 24 hours, causing day and night. It also orbits the Sun once every 365.25 days, a movement that, combined with the tilt of Earth's axis, produces the seasons. When the Northern Hemisphere is tilted towards the Sun, it experiences summer.
地球每 24 小时自转一圈，造成了昼夜更替。地球还绕太阳公转，每 365.25 天一圈，公转加上地轴倾斜共同形成了四季。当北半球向太阳倾斜时，北半球处于夏季。
The Moon orbits the Earth, and its changing appearance – phases from new moon to full moon – is due to the varying illumination by the Sun. Eclipses occur when the Sun, Earth, and Moon align: a solar eclipse when the Moon blocks sunlight to Earth, a lunar eclipse when the Earth blocks sunlight to the Moon.
月球绕地球运行，其形状变化——从新月到满月的月相——是由于太阳照射角度不同造成的。日食和月食发生在日地月成一直线时：月球遮住照向地球的太阳光为日食，地球遮住照向月球的太阳光为月食。
Published by TutorHao | 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