The medium in which the speed of light is half of the speed in air, if light travels from such medium to air, then for what angle of incidence light will do total internal refelction ?

Options

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

Answer

B, C

Explanation

Refractive index `n=c/v=(c)/(c//2)=2`
According to total internal reflection,
`I gt C`
`thereforesini gt sin C`
`thereforesin gt 1/n`
`thereforei gt sin^(-1)(1/2)`
`thereforesini gt1/2`
`therefore I gt 30^@`