What is the tube length of a compound microscope?

$A$ microscope consists of an objective of focal length $1.9 \,cm$ and an eyepiece of focal length $5 \,cm$. The two lenses are kept at a distance of $10.5 \,cm$. If the image is to be formed at the least distance of distinct vision, the distance at which the object is to be placed before the objective is (least distance of distinct vision is $25 \,cm$). (in $\,cm$)

The intermediate image formed by the objective of a compound microscope is

How should people wearing spectacles work with a microscope?

$(a)$ $A$ card sheet divided into squares each of size $1 \; mm^2$ is being viewed through a magnifying glass (a converging lens of focal length $9 \; cm$) held close to the eye. Where should the lens be held in order to view the squares distinctly with the maximum possible magnifying power?
$(b)$ What is the magnification in this case?
$(c)$ Is the magnification equal to the magnifying power in this case? Explain.

The focal lengths of the objective and the eyepiece of a compound microscope are $1 \, cm$ and $5 \, cm$ respectively. An object is placed at a distance of $1.1 \, cm$ from the objective. If the final image is formed at infinity,the magnifying power of the microscope is: