Two mirrors at an angle $\theta^{\circ}$ produce $5$ images of a point. The number of images produced when $\theta$ is decreased to $\theta^{\circ}-30^{\circ}$ is

Two plane mirrors $M_1$ and $M_2$ have a length of $20 \, m$ each and are $10 \, cm$ apart. $A$ ray of light is incident on one end of mirror $M_2$ at an angle of $53^{\circ}$. The number of reflections the light undergoes before reaching the other end is

Which one of the following statements is true?

Two plane mirrors $AB$ and $AC$ are inclined at an angle $\theta = 20^{\circ}$. $A$ ray of light starting from point $P$ is incident at point $Q$ on the mirror $AB$,then at $R$ on mirror $AC$,and again at $S$ on $AB$. Finally,the ray $ST$ goes parallel to mirror $AC$. The angle which the ray makes with the normal at point $Q$ on mirror $AB$ is: (in $^{\circ}$)

$A$ small plane mirror is placed at the center of a spherical screen of radius $R$. Light rays are incident on the mirror. If the mirror is rotated at a frequency of $n$ revolutions per second,what will be the speed of the reflected light spot on the screen?

$A$ ray of light is incident on a plane mirror at an angle of $30^\circ$. The deviation produced in the ray is....$^\circ$.