What should be the angle between two plane mirrors so that whatever be the angle of incidence, the incident ray and the reflected ray from the two mirrors be parallel to each other

Options

A. `60^(@)`
B. `90^(@)`
C. `120^(@)`
D. `175^(@)`

Answer

B

Explanation

Angle of diveation =` 180^(@)`

Now `delta = (360 - 2theta)`
`implies 180 = 360 - 2 theta`
`implies theta = (180)/(2) = 90^(@)`