wavelength

The length, usually measured from crest to crest or from trough to trough, of one oscillation of a wave. As an example, the distance between two consecutive peaks of ocean waves is a measure of wavelength. For light, wavelength measurements indicate both the color and energy of the light. For example, x-rays have very short wavelengths, around 0.1 nm, and very high energies. Visible light ranges in wavelength from 400 nm to 700 nm, and is of intermediate energies. Radio wavelengths measure on the order of meters, and radio waves are not very energetic. For light, wavelenth and frequency are inversely proportional.