A bar magnet is passing through a conducting loop of radius R with… | JEE Main 2021 (27 Aug, Shift 1)

Q23JEE Main 2021 · 27 AUG · SHIFT 1Medium

Lenz's Law, Eddy Currents & Induced Electric Field

A bar magnet is passing through a conducting loop of radius R with velocity $v$ . 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:

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Answer: (c)

As the N end approaches and passes the loop, flux increases quickly, giving a sharp emf pulse.
As the S end leaves, the flux decreases, giving a pulse of the opposite sign.
While the uniform middle part passes, flux hardly changes, so emf is nearly zero; the pulses are $l/v$ apart.
So the curve has two opposite pulses separated by $l/v$ ; with the chosen sign convention this is (c).

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Lenz's Law, Eddy Currents & Induced Electric Field question from JEE Main 2021 (27 Aug, Shift 1)

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