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Question: The velocity of light in a medium is half its velocity in air. If ray of light emerges from such a m...

The velocity of light in a medium is half its velocity in air. If ray of light emerges from such a medium into air, the minimum angle of incidence, at which it will be totally internally reflected, is-

A

150

B

300

C

450

D

600

Answer

300

Explanation

Solution

m = CC/2\frac { \mathrm { C } } { \mathrm { C } / 2 }= 2 so for TIR, i ³ C

sin i ³ sin C Ž sin i ³ 1μ\frac { 1 } { \mu } or i ³ 300