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

Options

A. `15^(@)`
B. `30^(@)`
C. `45^(@)`
D. `60^(@)`

Answer

B

Explanation

`v_(m)=(1)/(2)c`
`mu=(c)/(V_(m))=(c)/((1)/(2)c)=2` or `(1)/(sini_(c))=2`
or `sini_(c)=(1)/(2) or i_(c)=30^(@)`