Question

State Brewster's Law.
The polarising angle of a transparent medium is ${60}^{\circ }$. Find the refractive index and the angle of refraction $(\tan {60}^{\circ }=\sqrt{3})$.

Answer 1

Brewster's law states that maximum polarisation of the light is achieved if the ray is allowed to fall on the surface such that angle between the reflected and the refracted ray is ${90}^o$. The angle of incidence of light in that case is known as Brewster's angle or polarising angle $\left(i_p\right)$.
Given : $i_p={60}^o$
Refractive index $n=\tan i_p$
$⟹n=\tan {60}^o=\sqrt{3}$
Angle of refraction $r={90}^o-i_p={90}^o-{60}^o={30}^o$