$A$ rod of length $10\, cm$ lies along the principal axis of a concave mirror of focal length $10\, cm$ in such a way that its end closer to the pole is $20\, cm$ away from the mirror. The length of the image is ......$cm$.

The radius of curvature of a concave mirror is $40 \ cm$ and the size of the image is twice that of the object. The object distance is $... \ cm$.

An object is gradually moving away from the focal point of a concave mirror along the axis of the mirror. The graphical representation of the magnitude of linear magnification $(m)$ versus distance of the object from the mirror $(x)$ is correctly given by
(Graphs are drawn schematically and are not to scale)

Write the relationship between the radius of curvature and the focal length for a spherical mirror.

The focal length of a concave mirror is $f$ and the distance from the object to the principal focus is $x$. The ratio of the size of the image to the size of the object is

The direction of a ray of light incident on a concave mirror is shown by $PQ$, where $PQ$ is parallel to the principal axis. The direction in which the ray would travel after reflection is shown by four rays marked as $A$, $B$, $C$ and $D$. Which of the four rays correctly shows the direction of the reflected ray?