JEE Main 2021PhysicsElectromagnetic InductionHardNumerical

JEE Main 2021Electromagnetic Induction Question with Solution

JEE Main 2021 (25 Jul Shift 1)

Question

A circular conducting coil of radius 1 m is being heated by the change of magnetic field B passing perpendicular to the plane in which the coil is laid. The resistance of the coil is 2 μΩ. The magnetic field is slowly switched off such that its magnitude changes in time as  

B=4π×10-3 T1-t100

The energy dissipated by the coil before the magnetic field is switched off completely is E=______mJ.

Enter your answer

Show full solutionCorrect answer: 80
Correct answer
80

Step-by-step explanation

ϕ=B·S

ϕ=4π×10-31-t100·πR2

ϕ=4×10-3×121-t100

ε=-dϕdt

ε=-ddt4×10-31-t100

ε=4×10-31100=4×10-5 V

When B=0

1-t100=0

t=100 sec

Heat =ε2Rt

Heat =4×10-522×10-6×100 J

Heat =16×10-10×1002×10-6 J

Heat =0.08 J

Heat =80 mJ

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About this question

This is a previous-year question from JEE Main 2021, covering the Electromagnetic Induction chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.