# Anatomy of a wave

• A wave is a vibration or oscillation that travels through space and transfers energy
• It transfers energy from one place to another, but it does not transfer matter
• Matter oscillates, with no net displacement

There are two types of waves in medium

Transverse waves – particles of the medium move perpendicular to the direction of the wave trave

Longitudinal waves – particles of the medium move in a direction parallel to (oscillates back and forth in) the direction of wave travel

• These waves are made up of compressions and rarefactions
• Often, this is modelled using a pressure v time graph to make it similar to a transverse wave

### Terminology

 Crest (peak) The highest point of a wave Trough The lowest point of a wave Equilibrium position The vertical midpoint of a wave Wavelength (λ) The distance between two crests or troughs (m)The distance between two points in the same phase Amplitude The maximum displacement of a wave peak or trough from equilibrium (m) Frequency (f) The number of waves passing a point per second (Hz) Period (T) The time taken for a wave to complete a wavelength/cycle (s)

### Period-frequency equation

T = 1/f

f = 1/T

Speed of a wave

vwave =  λ/T = λ.f

For the speed of light, this becomes:

c = λ.f