Question

Three coaxial circular wire loops and a stationary observer are positioned as shown in figure. From the observer's point of view, a current $I$ flows counter clockwise in the middle loop, which is moving towards the observer with a velocity $v$. Loops A and B are stationary. This same observer would notice that.

• A. Clockwise currents are induced in loops A and B.
• B. Counter clockwise currents are induced in loops A and B.
• C. A clockwise current is induced in loop A, but a counter clockwise current is induced in loop B.
• D. A counter clockwise current is induced in loop A, but a clockwise current is induced in loop B.

Answer 1

Answer: (C)

A clockwise current is induced in loop A, but a counter clockwise current is induced in loop B.

The magnetic flux in loop A shall increase while the magnetic flux in loop B shall decrease. From Lenz's law, the induced current in loop A will decrease the flux in loop A and induced current in loop B shall increase the flux in loop B. Hence clockwise current is induced in loop A and counterclockwise current is induced in loop B.