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Saturday, 10 October

JEE Main 2020 · PhysicsMultiple choiceSingle correctHardMulti-step

JEE Main 6 September 2020, Shift 2, Physics Q12

Question 12 of 75 in this shift, Physics question 12 of 25.

Two identical electric point dipoles have dipole moments p1⃗=pi^\vec{p_1}=p\hat{i} and p2⃗=−pi^\vec{p_2}=-p\hat{i} and are held on the xx axis at distance 'a' from each other. When released, they move along the x-axis with the direction of their dipole moments remaining unchanged. If the mass of each dipole is 'm', their speed when they are infinitely far apart is :
  1. (1)pa12πϵ0ma\frac{p}{a}\sqrt{\frac{1}{2\pi\epsilon_0 ma}}Official answer
  2. (2)pa1πϵ0ma\frac{p}{a}\sqrt{\frac{1}{\pi\epsilon_0 ma}}
  3. (3)pa32πϵ0ma\frac{p}{a}\sqrt{\frac{3}{2\pi\epsilon_0 ma}}
  4. (4)pa2πϵ0ma\frac{p}{a}\sqrt{\frac{2}{\pi\epsilon_0 ma}}

Official answer

Option 1

NTA final key (Sep 2020).

Chapter
Electrostatic Potential and Capacitance
Topic
Electric Dipoles
Idea tested
Interaction Potential Energy Between Two Dipoles

Same topic in other shifts

All Electric Dipoles questions
  1. 2 Apr 2026, Shift 1 · Q36Two short electric dipoles AA and BB having dipole moment p1p_1 and p2p_2 respectively are placed with their axis mutually perpendicular…MediumSingle correctHas a figure
  2. 4 Apr 2026, Shift 2 · Q36A rigid dipole undergoes a simple harmonic motion about its centre in the presence of an electric field E⃗1=E0 x^\vec E_1=E_0\,\hat x. If another…MediumSingle correct
  3. 7 Apr 2025, Shift 2 · Q37A dipole with two electric charges of 2 μ2\ \muC magnitude each, with separation distance 0.5 μ0.5\ \mum, is placed between the plates of a…MediumSingle correct
  4. 28 Jul 2022, Shift 1 · Q56Two electric dipoles of dipole moments 1.2×10−301.2\times10^{-30} Cm and 2.4×10−302.4\times10^{-30} Cm are placed in two different uniform electric…EasyNumerical value
  5. 2 Apr 2017 (offline) · Q14An electric dipole has a fixed dipole moment p⃗\vec{p}, which makes angle θ\theta with respect to xx-axis. When subjected to an electric…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 42 of the 174 JEE Main shifts held from 2017 to 2026.