An image formed by a convex mirror of focal length $30 \ cm$ is one-fourth the size of the object. The distance of the object from the mirror is ...... $cm$.

$A$ concave mirror has a focal length of $30 \, cm$. If the image formed is erect (virtual),at what distance from the mirror should an object be placed so that the image is three times the size of the object (in $, cm$)?

The graph between $u$ and $v$ for a convex mirror is

The distance of an object from a spherical mirror is equal to the focal length of the mirror. Then the image:

$A$ ray of light is incident on a concave mirror. It is parallel to the principal axis and its height from the principal axis is equal to the focal length of the mirror. The ratio of the distance of point $B$ (where the reflected ray intersects the principal axis) to the distance of the focus from the centre of curvature is ($AB$ is the reflected ray).

In the parallax method for the determination of the focal length of a concave mirror, the object should always be placed: