Question

A beam of light strikes a piece of glass at an angle of incidence $60^{\circ}$. The reflected beam is completely plane polarised. The refractive index of glass is

• A. $\sqrt{3}$
• B. $\frac{\sqrt{3}}{2}$
• C. $\frac{1}{\sqrt{3}}$
• D. $\frac{3}{2}$

Answer 1

Answer: (A)

Since the reflected beam is completely plane polarised the angle of incidence is equal to polarising angle.
At polarising angle of incidence $n =\tan _{ p } $
$ n =\tan 60^{\circ}=\sqrt{3}$