Question

A square loop of wire lies in the plane of the page. A decreasing magnetic field is directed into the page. The induced current in the loop is:

a) counterclockwise
b) clockwise
c) zero
d) up the left edge and from right to left along the top edge
e) through the middle of the page

Answer 1

A decreasing magnetic field into the plane of the wire loop induces a current, which by Lenz's and the right-hand rules, flows clockwise to oppose the change in flux.

Step-by-step explanation:

When a square loop of wire experiences a decreasing magnetic field directed into the page, an induced current is generated due to Faraday's law of electromagnetic induction. According to Lenz's Law, the induced current will flow in such a direction as to oppose the change in magnetic flux through the loop. Hence, with a decreasing magnetic field into the page, the induced current aims to maintain the field by creating its own magnetic field in the same direction. Applying the right-hand rule, if we point the thumb of the right hand in the direction that the induced magnetic field is trying to maintain (into the page), the fingers curl in the direction of the induced current, which, in this case, is clockwise. Therefore, the answer is (b) clockwise.