A ray of light passes from vaccum into a medium of refractive index n. If the angle of incidence is twice the angle of refraction, then the angle of incidence is

Options

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

Answer

C

Explanation

`n=sini/(sin(i//2))=(2sin(i//2)cos(i//2))/sin(i//2)`
Solving we get, `i=2 cos^-1(n//2)`