The aperture of a telescope is made large,because

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

The focal length of the objective lens of a telescope is $30 \text{ cm}$ and that of its eye lens is $3 \text{ cm}$. It is focused on a scale at a distance $2 \text{ m}$ from it. The distance of the objective lens from the eye lens to see the clear image is: (in $\text{ cm}$)

$A$ simple telescope consisting of an objective of focal length $60\,cm$ and a single eye-lens of focal length $5\,cm$ is focused on a distant object in such a way that parallel rays emerge from the eye-lens. If the object makes an angle of $2^o$ at the objective,the angular width of the image is.....$^o$

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:

The final image formed by an astronomical telescope is