The minimum magnifying power of a telescope is $M$. If the focal length of its eye lens is halved, the magnifying power will become:

For a telescope in normal adjustment,the length of the telescope is found to be $27 \, cm$. If the magnifying power of the telescope at normal adjustment is $8$,the focal lengths of the objective and the eyepiece are respectively:

$A$ telescope has an eyepiece of focal length $5\, cm$ and an objective lens of focal length $60\, cm$. It is focused on a distant object such that the rays emerge from the eyepiece as parallel rays. Find the angular width of the image in degrees $(^o)$ if the object subtends an angle of $2^o$ at the objective.

$A$ small telescope has an objective of focal length $140 \ cm$ and an eyepiece of focal length $5.0 \ cm$. The magnifying power of the telescope for viewing a distant object is:

$A$ telescope has an objective lens of focal length $144\, cm$ and an eyepiece of focal length $6\, cm$. Find the magnifying power of the telescope for normal adjustment.

What is the tube length of a telescope?