The length of a telescope is $36 \ cm$. The focal lengths of its lenses can be

$A$ planet is observed by an astronomical telescope having an objective lens of focal length $16 \, m$ and an eye-piece of focal length $2 \, cm$. Find the correct statement.

The length of an astronomical telescope for normal vision (relaxed eye) ($f_o$ = focal length of objective lens and $f_e$ = focal length of eye lens) is

The large aperture of an astronomical telescope is used to:

In a reflecting telescope,a secondary mirror is used to:

$A$ telescope has an objective of focal length $50 \text{ cm}$ and an eyepiece of focal length $5 \text{ cm}$. The least distance of distinct vision is $25 \text{ cm}$. The telescope is focused for distinct vision on a scale $200 \text{ cm}$ away. The separation between the objective and the eyepiece is.......$\text{cm}$.