Lenz's law: A closed, circular loop has a counter-clockwise current flowing through it as viewed by a person on the right, as shown in the figure. If a second closed circular loop with the same radius approaches this loop with constant velocity along a common axis as shown, in what direction will a current flow in the approaching loop as viewed by the person on the right?
A) clockwise
B) counter-clockwise
C) No current will be induced because the velocity of approach is constant.

Question

Lenz's law: A closed, circular loop has a counter-clockwise current flowing through it as viewed by a person on the right, as shown in the figure. If a second closed circular loop with the same radius approaches this loop with constant velocity along a common axis as shown, in what direction will a current flow in the approaching loop as viewed by the person on the right? 
A) clockwise 
B) counter-clockwise 
C) No current will be induced because the velocity of approach is constant.

Quizplus · Accepted Answer

According to Lenz's law, an induced current will flow in such a way as to oppose the change that produced it. As the second loop approaches the first with a constant velocity, the magnetic field in the first loop due to the current circulating through it will change. This change in magnetic field will induce a current in the second loop in such a way that it will produce a magnetic field that opposes the change. Since the approaching loop is moving towards the first loop, the induced current in the second loop must flow in such a way as to create a magnetic field that opposes this motion. This can be achieved by inducing a current that flows clockwise in the second loop as viewed by a person on the right.

Lenz's Law: a Closed, Circular Loop Has a Counter-Clockwise Current