question_answer

The velocities of light in two different mediums are\[2\times {{10}^{8}}m{{s}^{-1}}\]and\[2.5\times {{10}^{8}}m{{s}^{-1}}\]respectively. The critical angle for these mediums is

A)  \[{{\sin }^{-1}}\left( \frac{1}{5} \right)\]                               

B)  \[{{\sin }^{-1}}\left( \frac{4}{5} \right)\]

C)   \[{{\sin }^{-1}}\left( \frac{1}{2} \right)\]                              

D)  \[{{\sin }^{-1}}\left( \frac{1}{4} \right)\]