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A certain elastic conducting material is stretched into a circular loop. It is placed with its plane perpendicular to a uniform magnetic field B=0.8 T. When released the radius of the loop starts shrinking at a constant rate of 2 cm s1. The induced emf in the loop at an instant when the radius of the loop is 10 cm will be ______ mV.
PhysicsElectromagnetic InductionJEE MainJEE Main 2023 (29 Jan Shift 1)
Solution:
1690 Upvotes Verified Answer
The correct answer is: 10

According to the Faraday's law of electromagnetic induction, the emf induced in a conducting loop is given by, e=-dϕdt, here, t is time and ϕ=BA is magnetic flux.

Here, e=dϕdt=dBAdt=Bdπr2dt

=Bπ2rdrdt=2×π×0.1×0.8×2×10-2

 10 mV (rounded off)

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