A beam of light is partially reflected and partially refracted from a surface. The angle between reflected and refracted light ray is `90^(@)`. If the angle of refraction is `30^(@)`, the angle of incidence is

Options

A. `50^(@)`
B. `60^(@)`
C. `75^(@)`
D. `78^(@)`

Answer

B

Explanation

i = angle of incidence,
r = angle of reflection,
r' = angle of refraction
We know that, i =r. Also, r+r' + 90 = 180
`:. i + r' + 90 = 180`
i + 30 + 90 = 180
`:. i = 60^(@)`