The length of the tube of a microscope is $10 \, cm$. The focal lengths of the objective and eye lenses are $0.5 \, cm$ and $1.0 \, cm$ respectively. The magnifying power of the microscope is about:

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

The power of two convex lenses $A$ and $B$ are $8$ diopters and $4$ diopters respectively. If they are to be used as a simple microscope,the magnification of

In a compound microscope,the magnification will be large if the focal length of the eyepiece is:

When the length of a microscope tube increases,its magnifying power

In a microscope of tube length $10 \ cm$,two convex lenses are arranged with focal lengths of $2 \ cm$ and $5 \ cm$. The total magnification obtained with this system for normal adjustment is $(5)^{k}$. The value of $k$ is . . . . . . .