To increase the magnifying power of a telescope ($f_o$ = focal length of the objective and $f_e$ = focal length of the eye lens):

The diameter of the moon is $3.5 \times 10^3 \, km$ and its distance from the Earth is $3.8 \times 10^5 \, km$. Find the angle subtended by the moon at the eye when viewed through a telescope. The focal length of the telescope's objective is $4 \, m$ and the focal length of the eyepiece is $10 \, cm$. The angle is .......... $^o$.

If the tube length of an astronomical telescope is $105 \, cm$ and the magnifying power is $20$ for normal setting,calculate the focal length of the objective in $cm$.

On which of the following does the magnifying power of a telescope depend?

Magnification produced by an astronomical telescope for normal adjustment is $10$ and the length of the telescope is $1.1 \, m$. The magnification when the image is formed at the least distance of distinct vision $(D = 25 \, cm)$ is

What is the tube length of a telescope?