Brewster's angle

For a plane electromagnetic wavefront incident on a plane boundary between two dielectric media having different refractive indices, the angle of incidence at which transmittance from one medium to the other is unity when the wavefront is linearly polarized with its electric vector parallel to the plane of incidence. Note 1: Brewster's angle θ_B, is given by where n₁ and n₂ are the refractive indices of the respective media, and ε₁ and ε₂, their respective electric permittivities. Note 2: For a randomly polarized ray incident at Brewster's angle, the reflected and refracted rays are at 90° with respect to one another.