IGCSE CIE Physics: Waves – Key Points Explained | IGCSE CIE 物理：波 考点精讲

📚 IGCSE CIE Physics: Waves – Key Points Explained | IGCSE CIE 物理：波 考点精讲

Waves are a fundamental topic in IGCSE CIE Physics. Understanding wave properties, the electromagnetic spectrum, and behaviour such as reflection, refraction and diffraction is essential for the exam. This article provides a concise yet thorough revision guide covering all the key points you need to master for the waves topic.

波是IGCSE CIE物理的核心主题。掌握波的性质、电磁波谱以及反射、折射、衍射等行为对考试至关重要。本文提供一份简洁而全面的复习指南，涵盖波主题中你需要掌握的所有考点。

1. Wave Types: Transverse and Longitudinal | 波的类型：横波与纵波

Waves transfer energy without transferring matter. There are two main types of waves based on the direction of particle oscillation relative to energy transfer: transverse and longitudinal.

波传递能量而不传递物质。根据质点振动方向与能量传递方向的关系，波主要分为两类：横波和纵波。

In transverse waves, the oscillations are perpendicular (at right angles) to the direction of wave travel. Examples include light waves, water ripples, and all electromagnetic waves.

横波中，振动方向与波的传播方向垂直。例如光波、水波纹以及所有电磁波。

In longitudinal waves, the oscillations are parallel to the direction of energy transfer. These waves consist of regions of high pressure (compressions) and low pressure (rarefactions). Sound waves in air are a typical example.

纵波中，振动方向与能量传递方向平行。这类波由高压区（密部）和低压区（疏部）组成。空气中的声波是一个典型例子。

Seismic waves also illustrate both types: Primary (P) waves are longitudinal and faster; Secondary (S) waves are transverse and slower.

地震波也展示了两种类型：P波（纵波，速度较快）和S波（横波，速度较慢）。

2. Wave Terminology | 波的术语

To describe waves, several key terms are used:

为了描述波，需要使用几个关键术语：

Wavelength (λ): the distance between two successive points that are in phase, for example, crest to crest or compression to compression. Measured in metres (m).

波长 (λ)：两个相邻同相位点之间的距离，例如波峰到波峰或密部到密部。单位为米(m)。

Frequency (f): the number of complete waves passing a point per second. Unit: hertz (Hz).

频率 (f)：每秒通过某一点的完整波数。单位：赫兹(Hz)。

Amplitude: the maximum displacement of a point on the wave from its undisturbed position. It relates to the energy carried by the wave.

振幅：波上某点偏离其平衡位置的最大位移。振幅与波携带的能量有关。

Period (T): the time taken for one complete oscillation or one full wave to pass a point. T = 1 / f.

周期 (T)：一次完整振动或一个完整波通过某点所需的时间。T = 1 / f。

Wave speed (v): the speed at which the wave energy travels. Measured in m/s.

波速 (v)：波能量传播的速度。单位为m/s。

3. The Wave Equation v = f λ | 波速方程 v = f λ

The speed of a wave is related to its frequency and wavelength by

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