A light ray is travelling from air to medium, c is velocity of light in air and v is velocity of light in medium. The reflected and refracted rays are perpendicular to each other. The angle of polarisation is

Options

A. `theta_(P) = tan^(-1)(v//c)`
B. `theta_(P) = cos^(-1)(v//c)`
C. `theta_(P) = cot^(-1)(v//c)`
D. `theta_(P) = sin^(-1)(v//c)`

Answer

C

Explanation

`v_(a) = c, v_(m) = v, theta_(P) = ?`
`mu_(m) = (v_(a))/(v_(m)) = tan theta_(P)`
`:. theta_(P) = tan^(-1)((v_(a))/(v_(m))) = tan^(-1)((c)/(v))`
i.e. `theta_(P) = cot((v)/(c))`