The distance between consecutive crusts (or troughs) is the wavelength (X). The wavelength of electromagnetic radiation are expressed in meters (m), millimeters (mm). Wavelength of radio waves is measured in meters, microwaves in cm, IR in micrometers (1 pm) and Ultraviolet in nanometers (nm) and that of X-rays in angstrom (A).
The number of full cycles of the wave that pass a given point each second, as the wave moves through space is called the frequency. It is usually reported by cycles per second Or Hertz