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Saturday, 31 October

JEE Main 2022 · PhysicsMultiple choiceSingle correctMediumMulti-step

JEE Main 27 July 2022, Shift 1, Physics Q40

Question 40 of 90 in this shift, Physics question 10 of 30, Section A.

Two identical positive charges Q each are fixed at a distance of '2a' apart from each other. Another point charge q0_0 with mass 'm' is placed at midpoint between two fixed charges. For a small displacement along the line joining the fixed charges, the charge q0_0 executes SHM. The time period of oscillation of charge q0_0 will be :
  1. (1)4π3ε0ma3q0Q\sqrt{\frac{4\pi^3\varepsilon_0 ma^3}{q_0Q}}Official answer
  2. (2)q0Q4π3ε0ma3\sqrt{\frac{q_0Q}{4\pi^3\varepsilon_0 ma^3}}
  3. (3)2π2ε0ma3q0Q\sqrt{\frac{2\pi^2\varepsilon_0 ma^3}{q_0Q}}
  4. (4)8π3ε0ma3q0Q\sqrt{\frac{8\pi^3\varepsilon_0 ma^3}{q_0Q}}

Official answer

Option 1

NTA final key.

Chapter
Electric Charges and Fields
Topic
Coulomb's Law
Idea tested
Small Oscillations of a Displaced Charge

Same idea in other shifts

Asked 3× in all
  1. 24 Feb 2021, Shift 2 · Q10Two electrons each are fixed at a distance '2d'. A third charge proton placed at the midpoint is displaced slightly by a distance xx (…MediumSingle correct
  2. 25 Jul 2021, Shift 1 · Q28A particle of mass 1 mg and charge q is lying at the mid-point of two stationary particles kept at a distance '2 m' when each is carrying…MediumNumerical 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.