$A$ student measures the thickness of a human hair by looking at it through a microscope of magnification $100$. He makes $20$ observations and finds that the average width of the hair in the field of view of the microscope is $3.5 \; mm$. What is the estimate on the thickness (in $mm$) of hair?

The objective of a compound microscope is essentially

In order to increase the magnifying power of a compound microscope:

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

$A$ compound microscope is used to enlarge an object kept at a distance $0.03\,m$ from its objective,which consists of several convex lenses in contact and has a focal length of $0.02\,m$. If a lens of focal length $0.1\,m$ is removed from the objective,then by what distance must the eyepiece of the microscope be moved to refocus the image? (in $cm$)

In a compound microscope,the intermediate image is