When a beam of light is incident on a plane mirror,it is found that a real image is formed. The incident beam must be

$A$ light ray makes an angle of $10^o$ with the horizontal. It strikes a plane mirror inclined at an angle $\theta$ to the horizontal,and the reflected ray becomes vertical. What is the value of the angle $\theta$ in degrees?

The figure shows a cubical room $ABCD$ with the wall $CD$ as a plane mirror. Each side of the room is $3\,m$. $A$ camera is placed at the midpoint of the wall $AB$. At what distance should the camera be focused to photograph an object placed at $A$?

Two parallel mirrors $M_1$ and $M_2$ are separated by a distance $a$. An object is placed between them. What is the distance between the $n^{th}$ image formed by $M_1$ and the $n^{th}$ image formed by $M_2$?

$A$ plane mirror produces a magnification of

Two plane mirrors are placed at an angle of $60^\circ$. $A$ horizontal light ray is reflected by the first mirror and then by the second mirror. The total deviation will be ........... $^\circ$.