A ray of light is reflected by two parallel plane mirrors $X$ and $Y$.
Which statement is correct?

A ray of light strikes a plane mirror PQ at an angle of incidence of ${30}^{\circ }$, is reflected from the plane mirror and then strikes a second plane mirror QR placed at right angles to the first mirror. The angle of reflection at the second mirror is : (a) ${30}^{\circ }$ (b) ${45}^{\circ }$ (c) ${60}^{\circ }$ (d) ${90}^{\circ }$ Draw a ray-diagram to illustrate your answer.

A light ray is incident at ${30}^{\circ }$ on mirror A which is placed at a right angle to mirror B. Find the angle of reflection for the ray reflected from mirror B.

Two mirrors meet at right angles. A ray of light is incident on one of the mirrors at an angle of $30$ degrees as shown in figure. Find the reflected angle for the reflection on the second mirror and sketch the reflected ray.