The image formed by an objective of a compound microscope is

The angular magnification of a simple microscope can be increased by increasing

$A$ card sheet divided into squares each of size $1\,mm^2$ is being viewed at a distance of $9\,cm$ through a magnifying glass (a converging lens of focal length $9\,cm$) held close to the eye. What is the angular magnification (magnifying power) of the lens?

$A$ 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, what is the effect on its magnifying power?

$A$ compound microscope has an eyepiece of focal length $10 \, cm$ and an objective of focal length $4 \, cm$. Calculate the magnification,if an object is kept at a distance of $5 \, cm$ from the objective so that the final image is formed at the least distance of distinct vision $(20 \, cm)$.

$A$ microscope is an optical instrument which: