Q. 13

# 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 10 m. Find the focal length of the objective and the magnifying power of the telescope.

Answer :

Given data-

The astronomical telescope is normally adjusted

Focal length of the eyepiece of the telescope, *f*e = 10 cm

Length of the tube, *L* = 1 m = 100 cm

To calculate the focal length of the objective, we have the relation-

Magnifying power of the telescope-

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