Question

The diameter of the moon is 3.5 × 103 km and its distance from the earth is  seen by a telescope, having the focal lengths of the objective and the eye-piece as 4m and 10 cm respectively; the diameter of the image of the moon will be approximately:

Solution

Correct option is

21o

 

  

As the angle subtended by moon on the objective of telescope

                       

the angular size of final image

                  

                        

SIMILAR QUESTIONS

Q1

A person cannot see objects clearly beyond 50 cm. The power of the lens to correct the vision is:

Q2

A presbyopic patient has near point as 30 cm and far point as 40 cm. The dioptric power for the corrective lens for seeing distant objects is:     

Q3

A terrestrial telescope is made by introducing an erecting lens of focal length f between the objective and eye-piece lenses of an astronomical telescope. This causes the length of the telescope tube to increase by an amount equal to:       

Q4

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

Q5

An astronomical telescope of ten-fold angular magnification has a length of 44 cm. The focal length of the objective is: 

Q6

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 subtends an angle of 2o at the objective, the angular width of the image is:       

Q7

Opera glasses have a minimum length of 20 cm and a magnifying power of 5 when viewing distant objects. The focal lengths of lenses used are: 

Q8

An astronomical telescope having an objective of focal length 100 cm is focused on the moon. Find the distance through which the eye-piece should be pulled back to focus an object situated at a distance 80 m from the objective:       

Q9

In a terrestrial telescope the focal length of erecting lens is 2 cm. The length of the telescope is 96 cm. If the magnifying power of the telescope is 10, then the focal lengths of eye-piece and objective are respectively:

Q10

The aperture of the largest telescope in the world is 5 m. if the separation between the moon and earth is 4 × 105 km and the wavelength of visible light is 5000 Å, then the minimum separation between the objects on the surface of the moon which can be just resolved is approximately: