The focal length of an objective of a telescope is 3 metre and diameter 15 cm . Assuming for a normal eye, the diameter of the pupil is 3 mm for its complete use, the focal length of eye piece must beA. 6 cmB. 6.3 cmC. 20 cmD. 60 cm

The focal length of an objective of a telescope is 3 metre and diamete

1.	The focal length of an objective of a telescope is 3 metre and diameter 15 cm . Assuming for a normal eye, the diameter of the pupil is 3 mm for its complete use, the focal length of eye piece must beA. 6 cmB. 6.3 cmC. 20 cmD. 60 cm
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The focal length of an objective of a telescope is 3 metre and diameter 15 cm . Assuming for a normal eye, the diameter of the pupil is 3 mm for its complete use, the focal length of eye piece must beA. 6 cmB. 6.3 cmC. 20 cmD. 60 cm

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