Question

When angle of incidence is 60⁰ on the surface of a glass slab, it is found that the reflected ray is completely polarized . The velocity of light in glass is :

• A. $\sqrt{2} \times 10^{8}ms^{- 1}$
• B. $\sqrt{3} \times 10^{8}ms^{- 1}$
• C. $2 \times 10^{8}ms^{- 1}$
• D. $3 \times 10^{8}ms^{- 1}$

Answer 1

Answer: (B)

$\sqrt{3} \times 10^{8}ms^{- 1}$

Answer 2

As reflected light is completely polarized, therefore,

$i_{p} = 60º$

$\mu = \tan i_{p} = \tan 60º = \sqrt{3}$

As $\mu = \frac{c}{v}\therefore v = \frac{c}{\mu} = \frac{3 \times 10^{8}}{\sqrt{3}} = \sqrt{3} \times 10^{8}ms^{- 1}$