JEE Main 2014PhysicsRay OpticsMediumMCQ

JEE Main 2014 — Ray Optics Question with Solution

JEE Main 2014 (06 Apr)

Question

A thin convex lens made from crown glass μ = 3 2  has focal length f⁡ . When it is measured in two different liquids having refractive indices 4 3  and 5 3 , it has the focal lengths f⁡ 1  and f⁡ 2  respectively. The correct relation between the focal lengths is :

Choose an option

Show full solutionCorrect option: B
Correct answer
B f⁡ 1 > f⁡  and f⁡ 2  becomes negative

Step-by-step explanation

Let [ 1 R 1 - 1 R 2 ] = x

∴ 1 f = [ 3 2 1 - 1 ] [ 1 R 1 - 1 R 2 ] ⇒ f = 2 x

When in liquid 1

1 f 1 = [ 3 2 4 3 - 1 ] [ 1 R 1 - 1 R 2 ] ⇒ f 1 = 8 x

When in liquid 2

1 f 2 = [ 3 2 5 3 - 1 ] [ 1 R 1 - 1 R 2 ] ⇒ f 2 = - 10 x

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About this question

This is a previous-year question from JEE Main 2014, covering the Ray Optics chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.