$A$ point object is placed mid-way between two plane mirrors at a distance $a$ apart. The plane mirrors form an infinite number of images due to multiple reflections. The distance between the $n^{th}$ order images formed in the two mirrors is

When one light ray is reflected from a plane mirror with $30^{\circ}$ angle of reflection,the angle of deviation of the ray after reflection is $.....^{\circ}$

Two plane mirrors are kept on a horizontal table making an angle $\theta$ with each other as shown schematically in the figure. The angle $\theta$ is such that any ray of light reflected after striking both the mirrors returns parallel to its incident path. For this to happen,the value of $\theta$ should be (in $^{\circ}$)

In the image given below,the total number of reflections of the light ray before it exits the system will be

$A$ point object is kept in front of a plane mirror. The plane mirror is performing $SHM$ with an amplitude of $2 \ cm$. The plane mirror moves along the $x$-axis,and the $x$-axis is normal to the mirror. The amplitude of the mirror is such that the object is always in front of the mirror. The amplitude of the $SHM$ of the image is ....... $cm$.

By what angle should $M_2$ be rotated,so that the light ray after reflection from both mirrors becomes horizontal? (The angle of incidence at mirror $M_1$ is $40^{\circ}$ and the angle between $M_2$ and the horizontal is $25^{\circ}$ as shown in the figure.)