Waves: Types, Properties and Examples

What is a Wave?

A wave is a disturbance that transfers energy from one point to another without transferring matter permanently from one place to another.

Types of Waves

• Mechanical waves: require a material medium (solid, liquid or gas) to travel through, e.g. sound waves and water waves.
• Electromagnetic waves: do not need a medium and can travel through a vacuum, e.g. light, radio waves, and X-rays.
• Transverse waves: the particles of the medium vibrate at right angles (perpendicular) to the direction the wave travels, e.g. light waves and waves on a string.
• Longitudinal waves: the particles vibrate parallel to (in the same direction as) the wave's travel, e.g. sound waves.

Key Properties of Waves

• Wavelength (λ): the distance between two successive identical points on a wave, e.g. crest to crest.
• Frequency (f): the number of complete waves (oscillations) passing a point per second, measured in Hertz (Hz).
• Amplitude: the maximum displacement of a particle from its rest position; relates to the energy/loudness or brightness of the wave.
• Wave speed (v): how fast the wave travels, given by the wave equation v = f × λ.
• Period (T): the time taken to complete one full oscillation, related to frequency by T = 1/f.

Behaviours of Waves

• Reflection: a wave bouncing back after hitting a surface.
• Refraction: a wave changing direction as it passes from one medium into another.
• Diffraction: a wave spreading out after passing through a gap or around an obstacle.

Importance of Studying Waves

Waves are central to how we communicate (radio, television, mobile phones), see (light), hear (sound), and are used in medicine (ultrasound, X-rays). Understanding wave properties helps explain and predict how these technologies and natural phenomena work.