Advertisements
Advertisements
प्रश्न
State the condition under which a large magnification can be achieved in an astronomical telescope.
Advertisements
उत्तर १
Condition under which a large magnification can be achieved in an astronomical telescope:
In astronomical telescope, the light is incident from infinity on the objective lens and it forms image at the focus of the objective lens and for large magnification the length between the lens is so adjusted that the final image is formed at the least distance of the distinct vision from the eyepiece
Magnification of astronomical telescope is
\[(M . P )_\max = - \frac{f_o}{f_e}(1 + \frac{f_e}{d})\] To have large magnification power, \[f_o\] must be large as possible and \[f_e\] must be as small as possible.
उत्तर २
By increasing the focal length of objective lens and at the same time keeping the focal length of eye peice minimum we can increase the magnifying power of telescope
संबंधित प्रश्न
Write two important advantages of reflecting telescope over a refracting telescope.
You are given three lenses of power 0.5 D, 4 D, and 10 D to design a telescope.
1) Which lenses should be used as objective and eyepiece? Justify your answer.
2) Why is the aperture of the objective preferred to be large?
Write the two important factors considered to increase the magnifying power?
(i) What is meant by resolving power of a telescope?
(ii) State any one method of increasing the resolving power of an astronomical telescope.
Draw a labelled ray diagram showing the formation of an image by a refracting telescope when the final image lies at infinity.
Draw a ray diagram of a refracting astronomical telescope when final image is formed at infinity. Also write the expression for its angular magnification (magnifying power).
Draw a ray diagram of astronomical telescope for the final image formed 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.
In an astronomical telescope in normal adjustment, a straight black line of length L is drawn on the objective lens. The eyepiece forms a real image of this line whose length is 𝑙. What is the angular magnification of the telescope?
