Conceptual Physics (12th Edition)

Published by Addison-Wesley
ISBN 10: 0321909100
ISBN 13: 978-0-32190-910-7

Chapter 25 - Think and Explain: 63

Answer

The electromagnet is ac.

Work Step by Step

The ac magnetic field continually changes the magnetic field in the copper ring. This induces a current in the copper ring, turning it into an electromagnet. The ring's field continually opposes the original field produced by the iron-core electromagnet, and the ring is continually repelled by it. The ring hovers at a position at which the repulsive force just balances the copper ring's weight.
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.