Question

The figure shows two parallel loops of wire having a common axis. The smaller loop (radius) is above the larger loop (radius R) by a distance x >> R. Consequently, the magnetic field due to the counterclockwise currenti in the larger loop is nearly constant throughout the smaller loop. Suppose that r, the radius of the smaller loop is increasing as the loop heats up, at the constant rate dr/dt. R in the smaller loop, find (c) the direction of the induced current. Select one O a counterclockwise O b. clockwise

Answer 1

The bigger loop has current counterclockwise, which result in a magnetic field in the upward direction. This magnetic field passes through smaller loop is constant, untill the radius of smaller loop starts increasing, after which the magnetic field lines passing through the smaller loop also increases. Now, current should be induced in such a way that the net magnetic field lines should decrease. This will happen when magnetic field due to induced current act in opposite direction, I.e.in downward direction. For magnetic field due to induced current to be in downward direction, induced current must flow in a clockwise sense.

Hence, direction of induced current must be clockwise.

Hope it helps.

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