Two plane mirrors are inclined to each other such that a ray of light incident on the first mirror and parallel to the second is reflected from the second mirror parallel to the first mirror. Determine the angle between the two mirrors:

Options

A. `30^(@)`
B. `45^(@)`
C. `60^(@)`
D. `75^(@)`

Answer

C

Explanation

Let the angle between the two mirrors be `theta`. Ray PQ is parallel to mirror `M_(1)` and RS is parrallel to `M_(2)`.

So, `angle M_(1)RS=angle ORQ =angle M_(1)OM_(2)=theta`
Similarly,
`angle M_(2)QP = angle OQR =angle M_(2)OM_(1)=theta`
`therefore " In "Delta ORQ`,
`3theta=180^(@)`
`theta=60^(@)`