There are several ways to measure and describe light waves. Wavelength is the distance from the top of one wave, called the crest, to the top of the next wave. Longer waves carry a relatively small amount of energy. Radio waves, which are actually a type of light, not sound, waves like you may think, are an example of long waves. Shortwaves, like ultraviolet light and gamma radiation, carry lots of energy. The frequency of a wave is the number of wavelengths that pass a fixed point in a period of time. Wavelength and frequency are inversely related. A wave with a higher frequency has a shorter wavelength and a wave with a lower frequency has a longer wavelength.