An object is placed $40\;cm$ from a concave mirror of focal length $20\;cm.$ The image formed is

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 placed in front of a concave mirror of focal length $0.15 \,m$ produces a virtual image,which is twice the size of the object. The position of the object with respect to the mirror is ........... $cm$. (in $.5$)

Assertion $(A):$ The relation among $u, v$ and $f$ for a spherical mirror is valid only for mirrors whose sizes are very small compared to their radii of curvature.
Reason $(R):$ The laws of reflection are strictly valid for plane surfaces but not for large spherical surfaces.

What will be the height of the image when an object of height $2 \ mm$ is placed on the principal axis of a convex mirror (of radius of curvature $40 \ cm$) at a distance of $20 \ cm$ from the mirror?

An object of length $6 \ cm$ is placed at a distance of $4f$ on the principal axis of a concave mirror of focal length $f$. The length of the image will be ......$cm$.