Ray Optics

JEE Main level, single correct, medium

93 of 295

Question 93 of 295

A microscope is focused on an object at the bottom of a bucket. If liquid with refractive index 53\dfrac{5}{3} is poured inside the bucket, then microscope have to be raised by 30cm30cm to focus the object again. The height of the liquid in the bucket is :

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Answer: (A) 75cm75cm

In this case shift is given by, shift\text{shift}=d(1−1μ)=30cm=d\left(1-\dfrac{1}{\mu }\right)=30cm
⇒d[1−153]=30\Rightarrow d\left[1-\dfrac{1}{\dfrac{5}{3}}\right]=30
⇒d=30×52=75cm\Rightarrow d=\dfrac{30\times 5}{2}=75cm

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