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प्रश्न
Why should the objective of a telescope have large focal length and large aperture? Justify your answer.
उत्तर
The objective of a telescope have large focal length and large aperture because large focal length enhances the magnifying power of the telescope and large aperture help in collecting large amount of light coming from the object so that a bright image is obtained.
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संबंधित प्रश्न
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 ?
Write the two important factors considered to increase the magnifying power?
Draw a labelled ray diagram of an astronomical telescope to show the image formation of a distant object. Write the main considerations required in selecting the objective and eyepiece lenses in order to have large magnifying power and high resolution of the telescope.
Define its magnifying power and write the expression for it?
Draw a labelled ray diagram showing the formation of an image by a refracting telescope when the final image lies at infinity.
Read the following paragraph and answer the questions.
| A number of optical devices and instruments have been designed and developed such as periscope, binoculars, microscopes and telescopes utilising the reflecting and refracting properties of mirrors, lenses and prisms. Most of them are in common use. Our knowledge about the formation of images by the mirrors and lenses is the basic requirement for understanding the working of these devices. |
- Why the image formed at infinity is often considered most suitable for viewing. Explain
- In modern microscopes, multicomponent lenses are used for both the objective and the eyepiece. Why?
- Write two points of difference between a compound microscope and an astronomical telescope
OR
Write two distinct advantages of a reflecting type telescope over a refracting type telescope.
Draw a labelled ray diagram showing the image formation by a refracting telescope. Define its magnifying power.
Draw a ray diagram for the formation of image of an object by an astronomical telescope, in normal adjustment. Obtain the expression for its magnifying power.
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.
