Q. 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

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A

$\sqrt{3}$

B

$\frac{\sqrt{3}}{2}$

C

$\frac{1}{\sqrt{3}}$

D

$\frac{3}{2}$

Solution:

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}$

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