question_answer

Un-polarised light is travelling from a medium of refractive index 2 to a medium of refractive index 3. The angle of incidence is\[{{60}^{o}}\]. Then

A)  Reflected light will be partially polarized

B)  Reflected light will be plane polarised in a plane perpendicular to plane of incidence

C)  Refracted light will be plane polarised in a plane perpendicular to plane of incidence

D)  Refracted light will be plane polarised in a plane parallel to plane of incidence

Correct Answer: A

Solution :

Consider the situation shown below Brewster's angle for two media is given by \[\tan \,\,{{i}_{B}}=\frac{{{n}_{2}}}{{{n}_{1}}}=\frac{3}{2}\] \[\Rightarrow \] \[{{i}_{B}}={{\tan }^{-1}}(3/2)={{56}^{o}}\] Clearly,            \[i=\theta \ne {{i}_{B}}\] Thus, reflected  light is not plane polarised. It will be partially polarised.