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 angle of incidence, at which it will be totally internally reflected, is

Options

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

Answer

B

Explanation

`mu=(c)/(v)impliesmu=(c)/(c//2)=2` also for total internal reflection
`igtcimpliescsinigesincimpliessinige(1)/(mu)`
Hence `igesin^(-1)((1)/(mu))` or `ige30^(@)`