$A$ microscope is an optical instrument which:

$A$ man uses a thin convex lens of focal length $5 \, cm$ as a magnifying glass. He reads a book by holding it close to his near point of $25 \, cm$. What are the closest and farthest distances at which he can keep the book from the lens to read clearly?

In a compound microscope,cross-wires are fixed at the point:

The length of the compound microscope is $14 \, cm$. The magnifying power for a relaxed eye is $25$. If the focal length of the eye lens is $5 \, cm$,then the object distance for the objective lens will be.......$ cm$.

The image formed by an objective of a compound microscope is

$A$ simple microscope is used to see an object first in blue light and then in red light. Due to the change from blue to red light, its magnifying power