Question

The velocity of light in two different media are $2\times {10}^{8}m/s$ and $1.5\times {10}^{8}m/s$ respectively. The critical angle for these media is :

• A. $si{n}^{-1}\left(\frac{4}{3}\right)$
• B. $si{n}^{-1}\left(\frac{1}{2}\right)$
• C. $si{n}^{-1}\left(\frac{3}{4}\right)$
• D. $si{n}^{-1}\left(2\right)$

Answer 1

The correct option is C $si{n}^{-1}\left(\frac{3}{4}\right)$

Critical angle $\sin C=\frac{n_1}{n_2}=\frac{v_2}{v_1}$

So, $\sin C=\frac{1.5\times {10}^8}{2\times {10}^8}=\frac{3}{4}$

$⟹C={\sin }^{-1}\left(\frac{3}{4}\right)$