According to this, electromagnetic waves are characterized by amplitude, wavelength, period, frequency, and velocity. Amplitude is the distance from a wave's midpoint to its crest or trough. Remember that wavelength of an electromagnetic wave is the distance between crests and the period of an electromagnetic wave is the time between crests. This is not an especially useful description of velocity, however, because many applications of remote sensing make reference to wavelength and frequency , not wavelength and period . A very important point to make at this time is that this relationship holds for all waves.
Velocity always equals frequency times wavelength.
Beyond this, electromagnetic waves are a special case, because the velocity of electromagnetic waves is essentially constant. Because the speed of light is constant, you can see a simple inverse relationship between the frequency and wavelength of electromagnetic waves. As the frequency increases, the wavelength decreases, and the opposite is true as well. This chart indicates the relationship between wavelength and frequency. In this case, a particle description of electromagnetic radiation is more appropriate than a wave description.