question_answer

A ray of light travels from an optically denser to rarer medium.  The critical angle for the two media is C.  The maximum possible deviation of the ray will be   [KCET (Engg./Med.) 2002]

A)            \[\left( \frac{\pi }{2}-C \right)\]                                       

B)            2C

C)            \[\pi -2C\]                             

D)            \[\pi -C\]

Correct Answer: C

Solution :

                   When the ray passes into the rarer medium, the deviation is \[\delta =\varphi -0\]. This can have a maximum value of \[\left( \frac{\pi }{2}-C \right)\] for \[\theta =C\] and \[\varphi =\frac{\pi }{2}\].            When total internal reflection occurs, the deviation is \[\delta =\pi -2\], the minimum value of \[\theta \] being \[C.\]The maximum value of \[\delta =\pi -2C\].