$A$ boy stands straight in front of a mirror at a distance of $30 \ cm$ away from it. He sees his erect image whose height is $\frac{1}{5}$ of his real height. The mirror he is using is

$A$ concave mirror has a focal length $20\,cm$. The distance between the two positions of the object for which the image size is double of the object size is......$cm$

$A$ square wire frame of side $3 \ cm$ is placed $25 \ cm$ away from a concave mirror of focal length $10 \ cm$. What is the area enclosed by the image of the wire? (The centre of the square wire is on the axis of the mirror and the plane is perpendicular to the principal axis).

The focal length of a concave mirror is $f$ and the distance from the object to the principal focus is $x$. The magnification will be:

What is linear magnification? Obtain the equation of linear magnification for a concave mirror.

$A$ concave mirror produces an image of an object such that the distance between the object and the image is $20\ cm$. If the magnification of the image is $-3$,then the magnitude of the radius of curvature of the mirror is: (in $cm$)