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प्रश्न
Draw a labelled ray diagram showing the image formation by a refracting telescope. Define its magnifying power.
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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
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
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- 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.
Write the two important factors considered to increase the magnifying power?
Write two important limitations of a refracting telescope over a reflecting-type telescope.
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Define magnifying power of a telescope. Write its expression.
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.
A Galilean telescope is 27 cm long when focussed to form an image at infinity. If the objective has a focal length of 30 cm, what is the focal length of the eyepiece?
A lady cannot see objects closer than 40 cm from the left eye and closer than 100 cm from the right eye. While on a mountaineering trip, she is lost from her team. She tries to make an astronomical telescope from her reading glasses to look for her teammates. (a) Which glass should she use as the eyepiece? (b) What magnification can she get with relaxed eye?
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).
