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) $\frac{R}{3}$ Official answer
(2) $\frac{R}{2}$
(3) $2R$
(4) $\frac{3R}{2}$

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 3× in all

17 Mar 2021, Shift 1 · Q13The thickness at the centre of a plano convex lens is 3 mm and the diameter is 6 cm. If the speed of light in the material of the lens is…MediumSingle correct
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 108 of the 174 JEE Main shifts held from 2017 to 2026.