What is the angular magnification of a telescope if the focal lengths of the objective and eye lenses are $10 \ cm$ and $10 \ mm$ respectively,and the tube length is $11 \ cm$?

For an astronomical telescope,the focal length of the objective lens is $f_{0}$ and the eyepiece lens is $f_{e}$. Then the tube length of the telescope is . . . . . . .

An astronomical telescope has an objective and an eyepiece of focal lengths $40\, cm$ and $4\, cm$ respectively. To view an object $200\, cm$ away from the objective,the lenses must be separated by a distance of.....$cm$.

The focal length of the objective and the eyepiece of a telescope are $50\,cm$ and $5\,cm$ respectively. If the telescope is focused for distinct vision on a scale distant $2\,m$ from its objective,then its magnifying power will be

The magnifying power of a telescope is $9.$ When it is adjusted for parallel rays,the distance between the objective and eyepiece is $20\; cm.$ The focal lengths of the lenses are:

What is a telescope?