For a concave mirror,the minimum distance between a real object and its real image is ...........

Incident parallel rays make an angle of $5^{\circ}$ with the axis of a concave mirror of focal length $20 \ cm$. The perpendicular distance of the image from the axis is nearly $-$ (in $cm$)

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

The image formed by a convex mirror of focal length $30 \,cm$ is a quarter of the size of the object. The distance of the object from the mirror is (in $\,cm$)

If the distances of the object and its real image from the principal focus of a concave mirror are $16 \ cm$ and $9 \ cm$ respectively, then the focal length of the mirror is (in $cm$)

$A$ person wants a real image of his own,$3$ times enlarged. Where should he stand in front of a concave mirror of radius of curvature $30 \ cm$ (in $cm$)?