A ray of light passes from vacuum into a medium of refractive index `mu`, the angle of incidence is found to be twice the angle of refraction. Then the angle of incidence is :

Options

A. `cos^(-1)(mu/2)`
B. `2cos^(-1)(mu/2)`
C. `2sin^(-1)(mu)`
D. `2sin^(-1)(mu/2)`

Answer

B

Explanation

Given, `i=2r, mu=(sini)/(sinr)=(sin2r)/(sinr)=(2sinrcosr)/(sinr)`
`" "cosr=mu/2" or "r=cos^(-1)(mu/2)`
`" "i=2r=2cos^(-1)(mu/2)`