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 `theta` be the angle between the two mirrors.
`PQ||M_(1)O and RS||OM_(2)`
`because r+theta=(pi)/(2) and r +alpha=(pi)/(2)`

`rArr" "alpha=theta` and Similarly `beta=theta`
Hence In `DeltaROQ, 3theta=180^(@)`
`therefore theta=60^(@)`