question_answer

An incident ray of light is incident perpendicular to the face ab of a prism \[(\mu =1.5)\] as shown below. Find the largest value of the angle \[\phi \] so that the incident light is totally reflected back at the face ac of the prism:

A) \[Co{{s}^{-1}}\left( \frac{1}{2} \right)\]            

B) \[Co{{s}^{-1}}\left( \frac{3}{2} \right)\]

C) \[Co{{s}^{-1}}\left( \frac{2}{3} \right)\]

D) \[Co{{s}^{-1}}\left( \frac{1}{3} \right)\]