Two mirrors are inclined at an angle $\theta$ as shown in the figure. Light ray is incident parallel to one of the mirrors. Light will start retracing its path after third reflection if:

Q. Two plane mirrors are inclined at an angle $\theta$ as shown in the figure. Find the value of $\theta$ such that the light ray retraces its path after second reflection.

Q. Two mirrors $M_1$ and $M_2$ are inclined at angle $\theta$ as shown. A ray of light which is parallel to $M_2$ strikes $M_1$ and then strikes mirror $M_2$. After that it retraces its own path. Find $\theta$.

Q. Two plane mirrors are arranged at right angles to each other as shown in figure. A ray of light is incident on the horizontal mirror at an angle $\theta$ . For what value of $\theta$ the ray emerges parallel to the incoming ray after reflection from the vertical mirror?

Q. Two plane mirror A and B are inclined at angle $\theta (<{90}^o)$ to each other. A light ray parallel to mirror B is incident on mirror A and it becomes parallel to mirror A after reflection from mirror B. Find the value of angle $\theta$.

Q. Two plane mirror are arranged at right angles to each other as shown in figure .A ray of light is incident on the horizontal mirror at an angle of $\theta$.For what value of $\theta$ the ray emerges parallel to the incoming ray after reflection from the vertical mirror?