A ray of light passes from a denser medium to a rarer medium at an angle of incidence i. The reflected and refracted rays make an angle of `90^@` with each other. The angle of reflection and refraction are resepectively r and r'. The critical angle is given by :

Options

A. `sin^(-1) ` (sin r )
B. `sin^(-1) ` (tan r')
C. `sin^(-1) ` (tan i)
D. `sin^(-1) `(sin i)

Answer

C

Explanation

n `= (sin i)/(sin r.) and n = (1)/( sin i_(c ))`
`rArr " " sini_(c ) = (sin i)/(sin (90 - r)) = tani (therefore anglei = angler )`
`rArr i_(c ) = sin^(-1) (tani)`