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Question
The focal lengths of the objective and the eye-piece of a compound microscope are 1.0 cm and 2.5 cm respectively. Find the tube length of the microscope for obtaining a magnification of 300.
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Solution
Given:
fe = 2.5 cm, fo = 1 cm
Let d be the minimum distance which should be kept away from an eye to see = 25 cm.
Magnification of compound microscope,
`m = m_o xx m_e`
`m = L/f_o xx D/f_e`
Here we need to find L (Length of the microscope), D = 25 cm (near point) and m = 300.
`300 = L/1 xx (25/2.5)`
L = 30 cm
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