# Magnets can create power?

1. Jun 21, 2007

### eek3386

I know that electricity running through a circuit produces a magnetic field...does this work the other way around? Does a permanent magnet in a circuit produce electricity? A colleague of mine is trying to convince me that moving a magnet back and forth in the presence of a circuit can produce a small electrical field. True or not?

Thanks in advance for any help!

2. Jun 21, 2007

### G01

Yes, a magnet can produce a current in the following way. If you, let's say, shake a magnet near a wire in a circuit, the changing magnetic field caused by the shaking will create an electric field in the circuit, which will cause an electric current. This is described by Lenz's Law. The magnet doesn't actually "create power". That would be a violation of conservation of energy. What the magnet does is take the energy you put into shaking and transform it into the energy of the current using the fields

3. Jun 21, 2007

### eek3386

Are there certain formulas relating to this so I can actually calculate how much of an electric field is being produced?

4. Jun 21, 2007

### chroot

Staff Emeritus
5. Jun 21, 2007