Question

State Brewster’s law. The value of Brewster angle for a transparent medium is different for light of different colour. Give reason.

Answer 1

Brewster’s law :
The law states that the tangent of the polarising angle of incidence of a transparent medium is equal to its refractive index. The light incident at this angle when reflects back is perfectly polarised.
p = tan i_p
The refractive index of a material depends on the colour or wavelength of light. As the polarising angle depends on refractive index (p = tan i_p ), so it also depends on wavelength of light.