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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceSingle correctHardData or graph

JEE Main 27 August 2021, Shift 1, Physics Q14

Question 14 of 90 in this shift, Physics question 14 of 30, Section A.

A bar magnet is passing through a conducting loop of radius R with velocity vv. The radius of the bar magnet is such that it just passes through the loop. The induced e.m.f. in the loop can be represented by the approximate curve :

The figure, in words

Stem figure: a conducting loop (circle edge-on) of radius R drawn at left, and a cylindrical bar magnet of length l with N at the left end and S at the right end, with an arrow marked v pointing left under the magnet.
  1. (1)[figure: graph of emf versus t, a negative pulse first, then after an interval l/v (marked by a dashed double arrow) a taller positive pulse]Official answer
  2. (2)[figure: graph of emf versus t, two negative pulses of equal size separated by an interval l/v (marked by a dashed double arrow)]
  3. (3)[figure: graph of emf versus t, two positive pulses of equal size separated by an interval l/v (marked by a dashed double arrow)]
  4. (4)[figure: graph of emf versus t, a positive pulse first, then after an interval l/v (marked by a dashed double arrow) a negative pulse]

Official answer

Option 1

NTA final key.

Chapter
Electromagnetic Induction
Topic
Lenz's Law
Idea tested
Current Reversal During Magnet Pass-Through

Same topic in other shifts

All Lenz's Law questions
  1. 10 Apr 2023, Shift 2 · Q46A bar magnet is released from rest along the axis of a very long vertical copper tube. After some time the magnet willMediumSingle correct
  2. 11 Apr 2023, Shift 2 · Q47Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: A bar magnet dropped…EasyAssertion–reason
  3. 29 Jul 2022, Shift 1 · Q44A coil of inductance 1 H and resistance 100 Ω\Omega is connected to a battery of 6 V. Determine approximately : (a) The time elapsed…HardSingle correct
  4. 31 Aug 2021, Shift 2 · Q15A coil is placed in a magnetic field B⃗\vec{B} as shown below : A current is induced in the coil because B⃗\vec{B} is :EasyDiagram basedHas a figure
  5. 4 Sep 2020, Shift 1 · Q15A small bar magnet is moved through a coil at constant speed from one end to the other. Which of the following series of observations will…MediumDiagram basedHas a figure

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. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.