Angular Magnification in Telescope

Q. The focal length of the objective and eye piece of a telescope are respectively 60 cm and 10 cm. The magnitude of the magnifying power when the image is formed at infinity is

1. 50
2. 6
3. 70
4. 5

Q. An astronomical telescope has an objective of focal length $100\text{cm}$ and an eye-piece of focal length $2\text{cm}$. The telescope is focused to see an object at $20\text{km}$ from the objective such that the final image is formed at infinity. Find the length ($l$) of the tube and the angular magnification ($m$) produced.

1. $100\text{cm},-50$
2. $100\text{cm},-25$
3. $102\text{cm},-25$
4. $102\text{cm},-50$

Q. When diameter of the aperture of the objective of an astronomical telescope is increased, its

1. Magnifying power is increased and resolving power is decreased
2. Magnifying power and resolving power both are increased
3. Magnifying power remains the same but resolving power is increased
4. Magnifying power and resolving power both are decreased

Q. The magnifying power of an astronomical telescope is 8 and the distance between the two lenses is 54 cm. The focal length of eye lens and objective lens will be respectively

1. 6 cm and 48 cm
2. 48 cm and 6 cm
3. 8 cm and 64 cm
4. 64 cm and 8 cm

Q. A telescope has objective and eye-piece of focal lengths 200 cm and 2 cm respectively. The magnifying power of the telescope for normal vision is

1. 90
2. 108
3. 100
4. 198

Q. Why don't we have a simple telescope?

1. We would need a convex lens of huuugeeeee focal length!
2. \N
3. We do have simple telescopes.
4. All this is not in syllabus, i don't care.

Q. What will be the expression for the angular magnification produced by the telescope?

1. $m_{\theta }=\frac{f_o}{f_e}$
2. $m_{\theta }=\frac{1+f_e}{f_o}$
3. $m_{\theta }=\frac{f_e}{f_o}$
4. $m_{\theta }=\frac{1+f_o}{f_e}$

Q. For astronomical telescope
i) focal length of its objective should be larger than that of eyepiece
ii) focal length of its eyepiece should be larger than that of objective
iii) aperture of objective should be wider than that of eye piece
iv) aperture of the objective should be less wider than that of eye piece

1. ii, iii, and iv are true
2. i and iii are true
3. i, ii. iii are true
4. ii, iii, iv are ture

Q. The diameter of the moon is $3.5\times {10}^{3}km$ and its distance from the earth is $3.8\times {10}^{5}km$. If it is seen through a telescope whose focal length for objective and eye lens are 4 m and 10 cm respectively, then the angle subtended by the image of the moon on the eye will be approximately

1. ${30}^{\circ }$
2. ${20}^{\circ }$
3. ${35}^{\circ }$
4. ${15}^{\circ }$

Q. If an object subtend angle of $2^{\circ }$ at eye when seen through telescope having objective and eyepiece of focal length $f_0=60cm$ and $f_e=5cm$ respectively then angle subtend by image at eye piece will be

1. ${50}^{\circ }$
2. ${16}^{\circ }$
3. ${24}^{\circ }$
4. ${10}^{\circ }$