For a plane mirror,the focal length is . . . . . . $m$.

Assertion : Plane mirror may form real image.
Reason : Plane mirror forms virtual image,if object is real.

An object is placed between two plane mirrors inclined at some angle to each other. If the number of images formed is $7$, then the angle of inclination is: (in $^{\circ}$)

Two plane mirrors are at right angles to each other. $A$ man stands between them and combs his hair with his right hand. In how many of the images will he be seen using his right hand?

An object $O$ is placed between two parallel plane mirrors $M_1$ and $M_2$. The distance of the object from $M_1$ is $6\,cm$ and from $M_2$ is $15\,cm$. The position of the $4^{th}$ image formed by mirror $M_1$ is:

$A$ thick plane mirror shows a number of images of the filament of an electric bulb. Of these,the brightest image is the