$A$ concave mirror of focal length $10 \, cm$ is immersed in water $(\mu = 4/3)$. The new focal length will be ...... $cm$.

Consider a concave mirror of $10 \,cm$ focal length illuminated by an object kept at a distance of $25 \,cm$. The distance at which the image is formed and its magnification respectively are

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 ........ $cm$.

The image formed by a convex mirror of a real object is larger than the object:

$A$ small linear object of length $b$ is placed on the axis of a concave mirror of focal length $f$ at a distance $u$ from its pole. What is the approximate length of the image?

Write the mirror equation for a spherical mirror.