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

$A$ concave mirror gives an image three times as large as the object placed at a distance of $20 \ cm$ from it. For the image to be real,the focal length should be ...... $cm$.

The figure shows a small concave mirror with $CP$ as its principal axis. $A$ ray $XY$ is incident on the mirror. Which of the four rays can be the reflected ray?

$A$ square wire frame of side $3 \, cm$ is placed at a distance of $25 \, cm$ from a concave mirror of focal length $10 \, cm$. The area of the image is ........ $cm^2$.

The image formed by a convex mirror of focal length $f$ is $(1/n)$ times the size of the object. The distance of the object from the mirror is:

Define the focal plane of a concave mirror.