Questions in Ray Optics and Optical Instruments

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If the telescope is reversed i.e. seen from the objective side
The focal length of the objective of a terrestrial telescope is 80 cm and it is adjusted for parallel rays, then its magnifying power is 20. If the focal length of erecting lens is 20 cm, then full length of telescope will be
An astronomical telescope has an angular magnification of magnitude 5 for distant objects. The separation between the objective and the eye piece is 36 cm and the final image is formed at infinity. The focal length $f_o$ of the objective and the focal length $f_e$ of the eye piece are
In an astronomical telescope, the focal lengths of two lenses are 180 cm and 6 cm respectively. In normal adjustment, the magnifying power will be
The magnifying power of an astronomical telescope for relaxed vision is 16. On adjusting, the distance between the objective and eye lens is 34 cm. Then the focal length of objective and eye lens will be respectively
In Gallilean telescope, if the powers of an objective and eye lens are respectively +1.25 D and – 20 D, then for relaxed vision, the length and magnification will be
The aperture of a telescope is made large, because
In Gallilean telescope, the final image formed is
The magnifying power of a telescope is 9. When it is adjusted for parallel rays, the distance between the objective and the eye-piece is found to be 20 cm. The focal length of the two lenses are
The focal length of the objective and eye piece of a telescope are respectively 60 cm and 10 cm. The magnitude of the magnifying power when the image is formed at infinity is

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