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JEE · NEET Previous Year Question

$The magnifying power of a telescope with tube length 60 cm is 5. What is the focal length of its eye piece?$

Topic: JEE PYQ

Answer: B. Full step-by-step solution below.

A $30 cm$
B $10 cm$
C $40 cm$
D $20 cm$

Correct answer: B

Solution

(b)m = \frac{f _{o}}{f _{e}} 5 = \frac{f _{o}}{f _{e}} f_{o} = 5 f_{e} f_{o} + f_{e} = 60 6 f_{e} = 60 f_{e} = 10

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