The magnifying power of an astronomical telescope for normal adjustment is given by:

The focal lengths of the objective and eye-piece of a telescope are $100 \ cm$ and $2 \ cm$ respectively. The moon subtends an angle of $0.5^o$ at the eye. If it is viewed through the telescope, the angle subtended by the moon's image will be......$^o$.

$A$ reflecting telescope utilizes

If the length of the tube of an astronomical telescope is $105 \, cm$ and its magnification power for normal adjustment is $20$,then the focal length of its objective lens will be ....... $cm$.

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.....$cm$.

There are four convex lenses $L_{1}, L_{2}, L_{3}$ and $L_{4}$ with focal lengths $2 \ cm, 4 \ cm, 6 \ cm$ and $8 \ cm$ respectively. Two of these lenses form a telescope of length $10 \ cm$ and magnifying power $4$. The objective and eye lenses are respectively: