Ray Optics

JEE Main level, numerical answer, medium

280 of 295

Question 280 of 295

A compound microscope consists of an objective lens of focal length 1cm1cm and an eye piece of focal length 5cm5cm with a separation of 10cm.10cm. The distance between an object and the objective lens, at which the strain on the eye is minimum is n40cm.\dfrac{n}{40}cm. The value of nn is.......

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Answer: 50

L=10L=10
Ve=∞{V}_{e}=\infty
ue=fe=5ue=fe=5
V0=10−5=5{V}_{0}=10-5=5
1v0−1u0=1f0\dfrac{1}{{v}_{0}}-\dfrac{1}{{u}_{0}}=\dfrac{1}{{f}_{0}}
15−1u0=11\dfrac{1}{5}-\dfrac{1}{{u}_{0}}=\dfrac{1}{1}
u0=−54cm{u}_{0}=-\dfrac{5}{4}cm
54=n40\dfrac{5}{4}=\dfrac{n}{40}
n=50n=50

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