# Formula Phase Velocity of a Wave Wavelength    Period

## Phase velocity

Unit
Phase velocity indicates the velocity of points of the same phase. For example, if you focus on a wave crest, then the phase velocity is the velocity of that wave crest.

The phase velocity of electromagnetic waves is the speed of light $$c$$.

## Wavelength

Unit
For example, wavelength is the distance between two wave crests.

## Period

Unit
Period is the time a wave crest takes to travel the distance $$2\pi$$.