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प्रश्न
You are given the following three lenses. Which two lenses will you use as an eyepiece and as an objective to construct an astronomical telescope ? Give reason
| Lenses | Power (D) | Aperture (cm) |
| L1 | 3 | 8 |
| L2 | 6 | 1 |
| L3 | 10 | 1 |
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उत्तर
For a telescope, lens L1 is chosen as objective, as its aperture and focal length are largest.
The lens L3 is chosen as eyepiece as its focal length is smallest.
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संबंधित प्रश्न
Why should the objective of a telescope have large focal length and large aperture? Justify your answer.
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Define its magnifying power and write the expression for it?
The focal lengths of the objective and eyepiece of a microscope are 1.25 cm and 5 cm respectively. Find the position of the object relative to the objective in order to obtain an angular magnification of 30 in normal adjustment.
An astronomical telescope is to be designed to have a magnifying power of 50 in normal adjustment. If the length of the tube is 102 cm, find the powers of the objective and the eyepiece.
(i) What is meant by resolving power of a telescope?
(ii) State any one method of increasing the resolving power of an astronomical telescope.
A small telescope has an objective lens of focal length 140 cm and an eyepiece of focal length 5.0 cm. Find the magnifying power of the telescope for viewing distant objects when
- the telescope is in normal adjustment,
- the final image is formed at the least distance of distinct vision.
For a terrestrial telescope used to observe objects on Earth such as mountains, trees, or players in a stadium, the final image must be:
A telescope in which the eye lens used is concave, so that the final image is erect, is popularly called a:
Modern telescopes often use a concave mirror rather than a lens for the objective primarily because:
