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प्रश्न
Draw a labelled ray diagram showing the image formation by a refracting telescope. Define its magnifying power.
उत्तर
Magnifying power: The magnifying power is the ratio of the angle α subtended at the eye by the final image to the angle β which the object subtends at the lens or the eye.
`m = beta/alpha`
= `(hf_o)/(f_eh) = f_o/f_e`
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संबंधित प्रश्न
Draw a schematic ray diagram of a reflecting telescope showing how rays coming from a distant object are received at the eyepiece.
Draw a labeled ray diagram to obtain the real image formed by an astronomical telescope in normal adjustment position. Define its magnifying power.
- A giant refracting telescope at an observatory has an objective lens of focal length 15 m. If an eyepiece of focal length 1.0 cm is used, what is the angular magnification of the telescope?
- If this telescope is used to view the moon, what is the diameter of the image of the moon formed by the objective lens? The diameter of the moon is 3.48 × 106 m, and the radius of lunar orbit is 3.8 × 108 m.
Why should the objective of a telescope have large focal length and large aperture? Justify your answer.
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
State the condition under which a large magnification can be achieved in an astronomical telescope.
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.
Draw a labelled ray diagram showing the formation of an image by a refracting telescope when the final image lies at infinity.
Define the term 'resolving power of a telescope'. How will the resolving power be effected with the increase in
(i) Wavelength of light used.
(ii) Diameter of the objective lens.
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.
