# How are the wavelength and frequency of electromagnetic radiation related?

The wavelength $l a m \mathrm{da}$ and frequency $\nu$ for any wave is related by the equation,
$l a m \mathrm{da} \nu = v$ where $v$ is the wave velocity.
For all electromagnetic waves, $v = c$ and hence,
$l a m \mathrm{da} \nu = c$ is the relationship, where $c$ is the speed of light in vacuum.
When light travels in some medium the velocity changes and for frequency $\nu$ constant (which is a fixed characteristic of the particular wave), the corresponding wavelength $l a m \mathrm{da}$ also changes.