Problem Faced by Surface Based Telescope and Telescopes in Space

Q. What are the difficulties in using ground based optical telescopes? How are they overcome?

Q.

The different types of reflecting telescope are

1. A. Newtonian

2. B. Cassegrain

3. C. Both A and B

4. D. None of the above

Q. If an astronomical telescope has objective and eye-pieces of focal length 200 cm and 4 cm respectively, then the magnifying power of the telescope for the normal vision is:

1. 42
2. 50
3. 58
4. 204

Q. an electric lamp and screen are placed on the table in a line at a distant of separation D to get the image of the lamp SRP required convex lens with focal length

Q. Explain the method of construction of an astronomical telescope.

Q. An astronomical refractive telescope has an objective of focal length 20 m and an eyepiece of focal length 2 cm. then

1. the image formed is inverted
2. the magnification is 1000
3. the length of the telescope tube is 20.02 m
4. all of these

Q. An astronomical telescope set for normal adjustment has a magnifying power $10$. If the focal length of the objective is $1.20m$, what is the focal length of the eye-piece?

Q. The magnifying power of an astronomical telescope is $0.5$. The power of its eyepiece is $10D$. What is the power of its objective

1. $-2D$
2. $+1D$
3. $+4D$
4. $+20D$

Q. An astronomical telescope has an eye piece of focal length $5cm$. If magnification produced is 14 in normal adjustment, then calculate the length of the telescope.

1. $9cm$
2. $50cm$
3. $55cm$
4. $75cm$

Q. The diameter of moon is $3.5\times {10}^{3}km$ and its distance from the earth is $3.8\times {10}^{5}km$. The focal length of the objective and eyepiece are $4m$ and $10cm$ respectively. The angle subtended by the diameter of the image of the moon will be approximately

1. $2^o$
2. ${20}^o$
3. ${40}^o$
4. ${50}^o$

Q. For the astronomical telescope, the focal length of objective lens is $f_o$ and the eye piece lens is $f_e$. Then the tube length of the telescope is _____

1. $L\ge f_o-f_e$
2. $L\ge f_o+f_e$
3. $L<f_o+f_e$
4. $L\le f_o-f_e$

Q. You are given following three lenses. Which two lenses will you see as an eyepiece and as an objective to construct an astronomical telescope?

Lenses	Power	Aperture
$L_1$	$3D$	$8cm$
$L_2$	$6D$	$1cm$
$L_3$	$10D$	$1cm$

Q. What are the difficulties in using ground based optical telescopes? How are they overcome? [ 3 Marks]

Q. The diameter of an object lens of a telescope is $5m$ and wavelength of light is $600A$. The limit of resolution of this telescope is

Q. What is meant by resolving power of a telescope?
State any one method of increasing the resolving power of an astronomical telescope.

Q. Fill in the blanks.
The type of lens used to make objective of an astronomical telescope is ________.

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

1. $M/2$
2. $2M$
3. $3M$
4. $4M$

Q. In which of the following instruments is final image erect?

1. Simple microscope
2. Compound microscope
3. Astronomical telescope
4. Galilean telescope

Q. In astronomical telescope, the final image is formed at

1. the focus of objective lens
2. the focus of the eye lens
3. Infinity
4. the least distance of distinct vision

Q. Write any two similarities between Astronomical telescope and terrestrial telescope.

Q. An astronomical telescope has an angular magnification of magnitude 5 for an object. The separation between the objective and the eye-piece is 36 cm. The final image is formed at infinity. The focal length $f_0$ of the objective and $f_e$, of the eye-piece are :

1. 50 cm and 10 cm
2. 45 cm and - 9 cm
3. 72 cm and 5 cm
4. 30 cm and 6 cm

Q. The objective of an astronomical telescope is a convex lens of ....................... focal length.

Q. For an astronomical telescope, the eye-piece has a focal length of 10 cm. When tube length is 1 m, the telescope is focussed for normal Vision of distant objects. The focal length of objections

1. 10 cm
2. 90 cm
3. 45 cm
4. 100 cm

Q. The image of a distant object as seen through an astronomical telescope is

1. Erect
2. Inverted
3. Disorted
4. None

Q. A telescope using light having wavelength $5000A^o$ and using lenses of focal $2.5$ and $30cm$. If the diameter of the aperture of the objective is $10cm$, then the resolving limit and magnifying power of the telescope is respectively

1. $5.1\times {10}^{-6}radand12$
2. $6.1\times {10}^{-6}radand12$
3. $5.1\times {10}^{-6}radand8.3\times {10}^{-2}$
4. $6.1\times {10}^{-6}radand8.3\times {10}^{-2}$

Q. In which of the following instruments is the final image inverted?

1. Projector
2. Camera
3. Microscope
4. Telescope

Q.

A lens having two spherical surfaces bulging outward is called ______________.

1. convex lens

2. plano-concave lens

3. concave lens

4. plano-convex lens

Q. All of the following statements are correct except

1. The total length of an astronomical telscope is the sum of the focal lengths of its two lenses
2. The image formed by the astronomical telescope is always erect because the effect of combination of the two lenses is divergent
3. The magnification of an astronomical telescope can be increased by decreasing the focal length of the eye- piece
4. The magnifying power of the refracting type of astronomical telescope is the ratio of the focal length of the objective to that of the eye-piece

Q. The focal length of the objective of a terrestrial telescope is $80cm$ and it is adjusted for parallel rays, then its power is $20$. If the focal length of erecting lens is $20cm$, then full length of the telescope will be

1. $124cm$
2. $100cm$
3. $164cm$
4. $84cm$

Q. The final image in an astronomical telescope with respect to object is :

1. real and inverted
2. real and erect
3. virtual and inverted
4. virtual and erect