# Features Common to All Waves

## Basic Concept

• Waves are disturbances that transfer energy from one point to another without transferring matter.
• They play a crucial role in many aspects of our lives including communication, medical diagnostics, weather forecasting and entertainment.

## Types of Waves

• All waves can be categorised into one of two types: mechanical waves, which require a medium (like water or air) to travel through, and electromagnetic waves, which can travel through a vacuum.
• Examples of mechanical waves include sound waves and seismic waves, while examples of electromagnetic waves include light waves, microwaves, radio waves and X-rays.

## Shared Characteristics

• Three fundamental features shared by all waves are wavelength, frequency and amplitude.
• Wavelength is the distance between two successive similar points of a wave such as from crest to crest or trough to trough.
• Frequency describes the number of waves that pass a given point in a certain amount of time. It is usually measured in hertz (Hz).
• Amplitude is the maximum distance that the particles of the wave’s medium vibrate from their rest position. In other words, it measures the ‘height’ of the wave when viewed as a graph.

## Speed, Frequency and Wavelength

• The speed of a wave (v) is related to its wavelength (λ) and its frequency (f) by the equation: v = f λ.
• Given two of these quantities, this formula can be rearranged to calculate the third.

## Wave Behaviours

• Waves generally show four main behaviours: reflection, refraction, diffraction and interference.
• Reflection is when a wave bounces off a surface.
• Refraction is when a wave changes direction (and speed) while moving from one medium to another.
• Diffraction is when a wave bends around the corners of an obstacle or through an aperture.
• Interference happens when two waves meet and combine to produce a new pattern.

## Wave Energy

• All waves carry energy without transporting matter.
• The amount of energy that a wave carries corresponds to its amplitude: higher amplitude waves convey more energy.

Understanding these fundamental properties and behaviours of waves will not only enable you to grasp more complex wave interactions, but it will also offer you insights into the fundamental processes of nature.