If in a compound microscope, the objective has a focal length of $1.0 \text{ cm}$, the eyepiece has a focal length of $2.0 \text{ cm}$, the tube length is $20 \text{ cm}$, and the near point for an observer is $25 \text{ cm}$, then the value of the magnification of the compound microscope will be . . . . . . .

$A$ convex lens of focal length $12.5 \ cm$ is used as a simple microscope. When the image is formed at infinity,the magnification is . . . . . . . (Near point for normal vision is $25 \ cm$)

The least distance of distinct vision is $25 \ cm$. Find the magnifying power of a simple microscope of focal length $5 \ cm$ if the final image is formed at the least distance of distinct vision.

The focal lengths of the objective and eye-lens of a microscope are $1 \,cm$ and $5 \,cm$ respectively. If the magnifying power for the relaxed eye is $45$,then the length of the tube is $....... \,cm$.

If the tube-length $(L)$ of a compound microscope increases, then its magnification . . . . . . .

$A$ 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 $\,cm$)