electromagnetic wave

An electromagnetic wave is a model used to represent electromagnetic rays. Its behaviour is consistent corresponding to a sinusoidal function and is characterised by three variables: a wavelength (distance between two maxima), a speed (speed of light, if in a vacuum) and a frequency. A light wave in an electromagnetic wave whose wavelength corresponds to the visible spectrum, i.e. between 380 and 780 nanometres. As for radio waves (including GPS signals), they have a far greater wavelength (sometimes kilometres).