Question

light coming from air impinges on a certain medium at normal incidence angle.if 80 % of its energy is transmitted at the interface, whats the brewster angle of this medium?

Answer 1

Hello!

It is stated here in the question that 80 % energy is transmitted at the interface.

Let us look at the definition of Brewsters angle :

Brewster's angle  is the angle of incidence, at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection. When unpolarized light is incident at this angle, the light that is reflected from the surface is therefore perfectly polarized.

Formula for Brewsters angle :

where n2 and n1 are the respective refractive indeces of the two mediums.

For a light wave passing from air to glass , the polarizing angle, p, is calculated to be

Ref index of air = 1, Ref index of glass =1.5

= 56°19′.