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Saturday, 31 October

JEE Main 2021 · PhysicsNumerical answerNumerical valueEasyCalculation

JEE Main 25 February 2021, Shift 2, Physics Q27

Question 27 of 90 in this shift, Physics question 27 of 30, Section B.

Two identical conducting spheres with negligible volume have 2.1 nC and −-0.1 nC charges, respectively. They are brought into contact and then separated by a distance of 0.5 m. The electrostatic force acting between the spheres is ____________ ×10−9\times 10^{-9} N. [Given : 4πε0=19×1094\pi\varepsilon_0 = \frac{1}{9 \times 10^9} SI unit]

Official answer

36

NTA final key.

Chapter
Electric Charges and Fields
Topic
Coulomb's Law
Idea tested
Charge Redistribution via Conduction

Same idea in other shifts

Asked 3× in all
  1. 6 Apr 2024, Shift 2 · Q42Two identical conducting spheres PP and SS with charge QQ on each, repel each other with a force 16 N. A third identical uncharged…MediumSingle correct
  2. 29 Jul 2022, Shift 2 · Q31Two identical metallic spheres A and B when placed at certain distance in air repel each other with a force of F. Another identical…MediumSingle correct

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.