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प्रश्न
Describe briefly the two main limitations and explain how far these can be minimized in a reflecting telescope ?
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उत्तर
Two limitations of refractive telescope are:
1. The lens used in refractive telescope are expensive.
2. The lens used for making refracting telescope have chromatic aberration and distortions.
They can be minimised by using reflecting type telescope, which use concave mirror rather than a lens for the objective. Reflecting type telescope has the following advantages:
1. They are free from chromatic aberration as mirror is used instead of lens.
2. There is no problem for mechanical support because weight of mirror is much less than the weight of the lens. It can be supported easily.
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संबंधित प्रश्न
A small telescope has an objective lens of focal length 144 cm and an eyepiece of focal length 6.0 cm. What is the magnifying power of the telescope? What is the separation between the objective and the eyepiece?
A small telescope has an objective lens of focal length 140 cm and an eyepiece of focal length 5.0 cm. What is the magnifying power of the telescope for viewing distant objects when
- the telescope is in normal adjustment (i.e., when the final image is at infinity)?
- the final image is formed at the least distance of distinct vision (25 cm)?
Write two important advantages of reflecting telescope over a refracting telescope.
Draw a labelled ray diagram of an image formed by a refracting telescope with the final image formed at infinity. Derive an expression for its magnifying power with the final image at infinity
With regard to an astronomical telescope of refracting type~ state how you will increase its:
1) magnifying power
2) resolving power
Draw a ray diagram showing the image formation of a distant object by a refracting telescope ?
The eyepiece of an astronomical telescope has a focal length of 10 cm. The telescope is focussed for normal vision of distant objects when the tube length is 1.0. m. Find the focal length of the objective and the magnifying power of the telescope.
Define the term ‘resolving power of a telescope’.
With the help of a ray diagram explain the working of a reflecting telescope.
Assertion: An astronomical telescope has an objective lens having large focal length.
Reason: Magnifying power of an astronomical telescope varies directly with focal length of the objective lens.
