When a beam of light goes from denser medium (`mu_d`) to rarer medium (`mu_r`), then it is generally observed that magnitude of angle of incidence is half that of angle of refraction. Then magnitude of incident angle will be-(here `mu=mu_d //mu_r`)

Options

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

Answer

C

Explanation

`mu_(d) sin I =mu_(r) sin 2i`
`mu_(d)=2 mu_(r) cosi`
`i=cos^(-1)((mu_(d))/(2mu_(r)))=cos^(-1)((mu)/2)`