A bar magnet is oriented above a copper ring,as shown in the figure.If the magnet is kept fixed while the ring is dropped,what is the direction of the current induced in the ring,as viewed from below the ring?
A)There is no current in the ring.
B)counterclockwise
C)clockwise

Question

A bar magnet is oriented above a copper ring,as shown in the figure.If the magnet is kept fixed while the ring is dropped,what is the direction of the current induced in the ring,as viewed from below the ring? 
A)There is no current in the ring. 
B)counterclockwise 
C)clockwise

Quizplus · Accepted Answer

According to Faraday's law of electromagnetic induction, a changing magnetic field induces an electric field, which in turn produces a current. In this case, as the ring is dropped, the magnetic field passing through the ring changes, and therefore an electric field and current are induced. By Lenz's law, the direction of the induced current opposes the change that produced it, which in this case is the decrease in magnetic flux through the ring. From below the ring, the magnetic field lines appear to be entering the ring from the left and exiting from the right. Therefore, the induced current must create a magnetic field that opposes this change. This can be achieved by creating a magnetic field that enters from the right and exits from the left, which corresponds to a clockwise current flow as viewed from below the ring. Therefore, the correct answer is C.

A Bar Magnet Is Oriented Above a Copper Ring,as Shown