A conducting ring is placed such that it is lying flat in the xy-plane. A magnetic field exists in the +z direction, and its strength is decreasing with time. Which of the following occurs?
A) No current is induced in the ring.
B) A current is induced, in the counter-clockwise direction, as viewed from above the xy-plane.
C) The situation is unclear because we do not know the initial conditions.
D) A current is induced, in the clockwise direction as viewed from above the xy-plane.

Question

Quizplus · Accepted Answer

According to Faraday's Law, a changing magnetic field induces an electromotive force (EMF) and hence a current in a closed circuit. The direction of the induced current is such that it produces a magnetic field opposing the change in the original magnetic field. In this case, since the magnetic field is decreasing with time, the induced current will produce a magnetic field in the +z direction, which is opposite to the original magnetic field. Applying the right-hand rule for current direction shows that the induced current will flow in a counter-clockwise direction, as viewed from above the xy-plane.

A Conducting Ring Is Placed Such That It Is Lying