The image formed by an objective of a compound microscope is

In a compound microscope,the focal length and aperture of the objective lens used are,respectively:

The magnification produced by the objective lens and the eye lens of a compound microscope are $25$ and $6$ respectively. The magnifying power of this microscope is

$A$ 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 $10 \, cm$) held close to the eye.
$(a)$ What is the magnification produced by the lens? How much is the area of each square in the virtual image?
$(b)$ What is the angular magnification (magnifying power) of the lens?
$(c)$ Is the magnification in $(a)$ equal to the magnifying power in $(b)$? Explain.

If the focal length of the objective lens and the eye lens are $4 \, mm$ and $25 \, mm$ respectively in a compound microscope,and the length of the tube is $16 \, cm$,find its magnifying power for the relaxed eye position.

Write the equation of magnification for a simple microscope when the image is formed at the near point.