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Friday, 9 October

JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 6 September 2020, Shift 2, Physics Q17

Question 17 of 75 in this shift, Physics question 17 of 25.

A double convex lens has power P and same radii of curvature R of both the surfaces. The radius of curvature of a surface of a plano-convex lens made of the same material with power 1.5 P is :
  1. (1)R3\frac{R}{3}Official answer
  2. (2)R2\frac{R}{2}
  3. (3)2R2R
  4. (4)3R2\frac{3R}{2}

Official answer

Option 1

NTA final key (Sep 2020).

Chapter
Ray Optics and Optical Instruments
Topic
Lens Maker's Formula
Idea tested
Plano-Convex Lens Focal Length

Same idea in other shifts

Asked 2× in all
  1. 8 Jan 2020, Shift 1 · Q25A point object in air is in front of the curved surface of a plano-convex lens. The radius of curvature of the curved surface is 30 cm and…EasyNumerical value

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 42 of the 174 JEE Main shifts held from 2017 to 2026.