JEE Main 2024 · PhysicsMultiple choiceSingle correctEasyCalculation

JEE Main 4 April 2024, Shift 1, Physics Q45

Question 45 of 90 in this shift, Physics question 15 of 30, Section A.

An effective power of a combination of 5 identical convex lenses which are kept in contact along the principal axis is 25 D. Focal length of each of the convex lens is :

(1)20 cmOfficial answer
(2)50 cm
(3)500 cm
(4)25 cm

Official answer

Option 1

NTA final key.

Chapter: Ray Optics and Optical Instruments
Topic: Lens Maker's Formula
Idea tested: Lenses in Contact

Same idea in other shifts

Asked 5× in all

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27 Aug 2021, Shift 2 · Q14Curved surfaces of a plano-convex lens of refractive index $\mu_1$ and a plano-concave lens of refractive index $\mu_2$ have equal radius…MediumSingle correctHas a figure

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.