Wavelength is the distance between successive peaks (or troughs) of a wave. Wavelength is related to the frequency and speed of a wave by the equation:

 

    speed = wavelength × frequency.

 

For example, a radio wave of wavelength 300 meters traveling at 300 million meters per second (the speed of light) has a frequency of 1 megahertz. The wavelength of a visible light wave, which can range from 390 to 780 nm (nanometers), determines its color.