$A$ microscope has an objective of focal length $1 \ cm$ and an eyepiece of focal length $6 \ cm$. If the tube length is $30 \ cm$ and the image is formed at the least distance of distinct vision,what is the magnification produced by the microscope? Take $D = 25 \ cm$.

$A$ compound microscope with an objective lens of focal length $1 \, cm$ and an eyepiece of $2 \, cm$ focal length has a tube length of $20 \, cm$. Calculate the magnifying power of the microscope,if the final image is formed at the least distance of distinct vision.

In which of the following is the final image erect?

$A$ 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 and the eyepiece of a microscope have focal lengths of $4 \, mm$ and $25 \, mm$,respectively. The objective produces a real image $30$ times the size of the object. The final image is viewed at infinity. The near point of the microscope user is at $25 \, cm$. The overall magnification of the microscope is

The intermediate image formed by an objective lens of a compound microscope is