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. `2sin^(-1)(n//2)`

Answer

Converging; real

Explanation

`i=2r`
`1 sin I =n sin r`
`implies2 sin i//2 cos i//2 = n sin i//2`
`implies cos i//2=(n//2)`
`implies i=2 cos^(-1) (n//2)`