JEE Main 2020PhysicsElectromagnetic InductionHardNumerical

JEE Main 2020 — Electromagnetic Induction Question with Solution

JEE Main 2020 (05 Sep Shift 1)

Question

Two concentric circular coils, C1 and C2, are placed in the XY plane. C1 has 500turns, and a radius of 1 cm. C2 has 200 turns and radius of 20 cm. C2 carries a time dependent current It=5t2-2t+3A where t is in s. The emf induced in C1in mV at the instant t=1s is 4x. The value of x is ..........

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Show full solutionCorrect answer: 5
Correct answer
5

Step-by-step explanation

I=5t2+2t+C

didt=(10t+2)

ϕsmall =BA=μ0IN22Rπr2

induced emf in small coil

e=dϕdt=μ0N22rπr2N1didt=μ0N1N2πr22R(10t-2)

at t=1

e=μ0N1N2πr22R8=4μ0N1N2πr2R=4(4π)10-7×20020×500×10-410-2π

=80×π2×10-7×10×102×10-2=8×10-4 volt=0.8 mV=4x

x=5

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About this question

This is a previous-year question from JEE Main 2020, 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.