In
physics and
electrical engineering the
reflection coefficient is a parameter that describes how much of an
electromagnetic wave is reflected by an impedance discontinuity in the transmission medium. It is equal to the ratio of the
amplitude of the reflected wave to the incident wave, with each expressed as
phasors. For example, it is used in
optics to calculate the amount of light that is reflected from a surface with a different index of refraction, such as a glass surface, or in an electrical
transmission line to calculate how much of the
electromagnetic wave is reflected by an impedance. The reflection coefficient is closely related to the
transmission coefficient. The
reflectance of a system is also sometimes called a "reflection coefficient".