A reflecting telescope has a large mirror for its objective with radius of curvature equal to 80 cm. The magnifying power of this telescope if eye piece used has a focal length of 1.6 cm is:

A telescope is used to resolve two stars separated by $4.6 \, \times \, 10^{-6}$ rad. If the wavelength of light used is 5460 $\overset{0}{A}$, what should be the aperture of the objective of the telescope? 

If you want to make Refracting Telescope, what components will you choose ?

Scientists identify the elements that are burning in the stars by using which of the following devices?

Two convex lenses of focal length 0.3 m and 0.05 m are used to make a telescope. The distance kept between them is equal to 

In an astronomical telescope of refracting type:

Four lenses of focal length $+15cm,+20cm,+150cm$ and $+250cm$ are available for making an astronomical telescope. To produce the largest magnification, the focal length of the eyepiece should be

A reflecting telescope utilises :

This question has Statement-1 and Statement-2. Of the four choices given after the Statements, choose the one that best describes the two Statements.
Statement 1 : Very large size telescopes are reflecting telescopes instead of refracting telescopes.
Statement 2 : It is easier to provide mechanical support to large size mirrors than large size lenses.

In the spectrum of light from a star, the wavelength of a particular line is measured to be $4747 $, while the actual wavelength of the line is $4700 $. What is the relative velocity ?

The objective of a telescope A has diameter 3 times that of the objective of telescope B, How much greater amount of light is gathered by A as compared to B?

In telescope, ratio of resolving power due to light of $\lambda=400\mathring {A}$ and $\lambda =6000\mathring {A}$ is ______

For an electron microscope, which of the following is false ?

 If an object subtend angle of $2^o$ at eye when seen through telescope having objective and eyepiece of focal length $f = 60\, cm $and $f = 5\, cm$ respectively than angle subtend by image at eye piece will be 

A telescope has an objective of focal length $50 cm$ and an eye-piece of focal length $5 m$ THe least distance of distinct vision is $25 cm$. The telescope is focused for distinct vission a scale $200 cm$ away from the objective.The separation between the two lenses is nearly 

Match the items given in A, B, C and D against their corresponding description given in 1, 2, 3, 4 and 5.
A. Astronomical telescope
B. Galilean Telescope
C. Simple Microscope
D. Compound Microscope

1. Contains one convex lens
2. Contains one concave lens
3. Contains a convex lens of large focal length in the objective and a convex lens of small focal length in the eye-piece
4. Contains a convex lens of small focal length in the objective and a convex lens of large focal length in the eye-piece
5. Contains a convex lens of large focal length in the objective and a concave lens of small focal length in the eye-piece. 

The sum of the focal lengths of the objective and an eyepiece, In case of an astronomical telescope is equal to : ( final image is at $\infty$)

By which instrument we collect the space information:

The focal lengths of the objective and the eyepiece of an astronomical telescope are 20 cm and 5 cm respectively. If the final image is formed at a distance of 30 cm from the eyepiece, find the separation between the lenses required for distinct vision

The focal length of the objective of an astronomical telescope is 1 m and it is in normal adjustment.Initially the telescope is focussed to a heavenly body. If the same telescope is to be focussed to an object at a distance of 21 m from the objective,then identify the correct choice

The focal lengths of the objective and eyepiece of a telescope are 60cm and 5cm respectively.The telescope is focused on an object 360cm from the objective and the final image is formed at a distance of 30cm from the eye of the observer. The length of the telescope is

In which of the following instruments is the final image virtual?

A planet is observed by an astronomical reflecting telescope having an objective of focal length $16 m$ and an eye-piece of focal length $2 cm$. Then :

An astronomical refracting telescope will have large angular magnification and high angular resolution, when it has an objective lens of