$A$ convex mirror of focal length $10\,cm$ is shown in the figure. $A$ linear object $AB = 5\,cm$ is placed along the optical axis. Point $B$ is at a distance of $20\,cm$ from the pole of the mirror. Then,the size of the image of $AB$ will be:

In an experiment to determine the focal length $(f)$ of a concave mirror by the $u-v$ method,a student places the object pin $A$ on the principal axis at a distance $x$ from the pole $P$. The student looks at the pin and its inverted image from a distance keeping his/her eye in line with $PA$. When the student shifts his/her eye towards left,the image appears to the right of the object pin. Then,

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......$cm$

$A$ 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 $, cm$)?

An object $2.5 \, cm$ high is placed at a distance of $10 \, cm$ from a concave mirror of radius of curvature $30 \, cm$. The size of the image is ........ $cm$.

An object is placed at a distance of $20 \ cm$ from the pole of a concave mirror of focal length $10 \ cm$. The distance of the image formed is