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प्रश्न
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.
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उत्तर
- When the image is formed at infinity, we can see it with minimum strain in the ciliary muscles of the eye.
- The multi-component lenses are used for both the objective and the eyepiece to improve image quality by minimising various optical aberrations in lenses.
- (a)The compound microscope is used to observe minute nearby objects whereas the telescope is used to observe distant objects.
(b) In a compound microscope the focal length of the objective is lesser than that of the eyepiece whereas in a telescope the focal length of the objective is larger than that of the eyepiece.
OR
(a) The image formed by a reflecting type telescope is brighter than that formed by refracting telescope.
(b) The image formed by the reflecting type telescope is more magnified than that formed by the refracting type telescope.
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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 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?
Why should the objective of a telescope have large focal length and large aperture? Justify your answer.
Write two important advantages of reflecting telescope over a refracting telescope.
"A telescope resolves whereas a microscope magnifies." Justify this statement ?
Write two important limitations of a refracting telescope over a reflecting-type telescope.
How is the working of a telescope different from that of a microscope?
An astronomical telescope uses two lenses of powers 10 dioptres and 1 dioptre. If the final image of a distant object is formed at infinity, calculate the length of the telescope
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.
