question_answer

Let the refractive index of a denser medium with respect to a rarer medium be \[{{n}_{12}}\] and its critical angle be \[{{\theta }_{C}}\]. At an angle of incidence A when light is travelling from denser medium to rarer medium, a part of the light is reflected and the rest is refracted and the angle between reflected and refracted rays is \[90{}^\circ .\]Angle A is given by:

A) \[\frac{1}{{{\cos }^{-1}}\left( \sin {{\theta }_{C}} \right)}\]

B) \[\frac{1}{{{\tan }^{-1}}\left( \sin {{\theta }_{C}} \right)}\]

C) \[{{\cos }^{-1}}\left( \sin {{\theta }_{C}} \right)\]           

D) \[{{\tan }^{-1}}\left( \sin {{\theta }_{C}} \right)\]