Tag: observing space: telescopes

A telescope of objective lens diameter $2m$ uses light of wavelength $5000 \mathring {A}$ for viewing starts. The minimum angular separation between two stars whose image is just resolved by their telescope is:

A tower $100m$ tall at a distance of $3$km is seen through a telescope having objective of focal length $140$cm and eyepiece of focal length $5cm$. Then the size of final image if it is at $25$cm from the eye?

The angular resolution of a radio telescope is to be ${ 0.100 }^{ 0 }$ when the incident beam of wavelength $ 3.00mm$ is used. What is minimum diameter required for the telescope's receiving dish? 

The focal lengths of the objective and eye lens of telescope are respectively $200\ cm$ and $5\ cm$. The maximum magnifying power of the telescope will be.

An observer looks at a distant tree
of height $10$ m with a
telescope of magnifying power of $20$. To the
observer the tree appears :

.

The angular resolution of a $10cm$ diameter telescope at a  wavelength of $5000A$ is of the order of 

In a terrestrial telescope, the telescope, the focal length of objective is 90 cm of inverting lens is 5 cm and of eye lens is 6 cm. If the final image is at 3  cm, then the magnification will be

The focal lengths of the objective and eye plece of astronomical telescope are $100cm$ and $2cm$ respectively. The magnitude of magnifying power of telescope for adjustment is

The focal length of an objective of a telescope is 3 meter and diameter 15 cm. Assuming for a normal eye, the diameter of the pupil is 3 mm for its complete use, the focal length of eye piece must  be

The diameter of the lens of a telescope is $1.22m$. The wavelength of light of $5000\mathring {A}$. The resolving power of the telescope is _____