question_answer

The speed of light in media \[{{M}_{1}}\] and \[{{M}_{2}}\] is \[1.5\times {{10}^{8}}m/s\] and \[2.0\times {{10}^{8}}\,m/s\] respectively. A ray of light enters from medium \[{{M}_{1}}\] to \[{{M}_{2}}\] at an incidence angle i. If the ray suffers total internal reflection, the value of i is      [AIPMT (M) 2010]

A)  equal to \[{{\sin }^{-1}}\left( \frac{2}{3} \right)\]

B)  equal to or less than \[{{\sin }^{-1}}\left( \frac{3}{5} \right)\]

C)  equal to or greater than \[{{\sin }^{-1}}\left( \frac{3}{4} \right)\]

D)  less than \[{{\sin }^{-1}}\left( \frac{2}{3} \right)\]

Correct Answer: C

Solution :

In total internal reflection, the angle of incidence (i) must be greater than critical angle C

and