IIT-JEE 2012 · Paper 2 · Physics Q16

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PhysicsMultiple correct+4Question 16 of 60

A current carrying infinitely long wire is kept along the diameter of a circular wire loop, without touching it. The correct statement(s) is(are)

The emf induced in the loop is zero if the current is constant.

The emf induced in the loop is finite if the current is constant.

The emf induced in the loop is zero if the current decreases at a steady rate.

The emf induced in the loop is finite if the current decreases at a steady rate.

Answer and worked solution

Official answer: A, C

Flux through the loop. The wire lies along a diameter, so the two halves of the loop are mirror images about the wire. The wire's field points into the plane on one side and out of it on the other, with equal magnitudes at mirror points. The net flux through the loop is zero whatever the current.

EMF. Since the flux is always zero, its rate of change is zero: no emf for a constant current or for a steadily changing one.

(A) True. (B) False. (C) True. (D) False.

(A), (C)

Topics:Faraday's and Lenz's laws Biot-Savart law

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IIT-JEE 2012 · Paper 2, Physics question 16