The aperture of a telescope is made large,because

The objective lens of a telescope has a focal length of $100 \, cm$. When the final image is formed at the least distance of distinct vision,the distance between the lenses is $105 \, cm$. Calculate the focal length of the eyepiece in $cm$.

$A$ giant refracting telescope at an observatory has an objective lens of focal length $15 \, m$. If an eyepiece of focal length $1.0 \, cm$ is used,what is the angular magnification of the telescope?

The focal length of the objective of a terrestrial telescope is $80 \, cm$ and it is adjusted for parallel rays. If its magnifying power is $20$ and the focal length of the erecting lens is $20 \, cm$,then the full length of the telescope will be......$cm$.

Where is the largest reflecting telescope in the world located? Mention the diameter of its reflector.

If the tube length of an astronomical telescope is $96 \ cm$ and the magnifying power is $15$ for normal setting,then the focal length of the objective is . . . . . . $cm$.