Magnetism - where does it's energy come from?

[Old Guy In Stanton]

I was playing around with a permanent magnet today and the thought suddenly struck me: There is an energy field here. Surely that must mean that it is using energy to maintain that field. But the field strength of a magnet doesn't decrease, does it? Whence, then, comes the continuous flow of energy that powers the field?

Edited March 6, 2016 by Old Guy In Stanton

[swansont]

There is no continuous flow of energy; nothing is required to maintain the field. Magnetic forces don't do work. The field has energy, but it's static - nothing going in or out.

[Sensei]

I was playing around with a permanent magnet today and the thought suddenly struck me: There is an energy field here. Surely that must mean that it is using energy to maintain that field. But the field strength of a magnet doesn't decrease, does it? Whence, then, comes the continuous flow of energy that powers the field?

 

In this video, showing the basic electromagnetic induction, source of energy, initial acceleration comes from gravity:

See how slowly magnet is passing through Copper pipe, in the second part of video.

It's three-four times as long as not magnetized piece of Bronze.

[derek w]

Whence, then, comes the continuous flow of energy that powers the field?

From the motion of the electrons

[swansont]

From the motion of the electrons

That's not it. Because the obvious followup is what's providing power to the electrons, and there is nothing doing this for a permanent magnet.

[Old Guy In Stanton]

If you stop the current flow in an electromagnet, the magnetic field collapses. Energy flow - input of energy from somewhere - is therefore obviously necessary for an electromagnet. So is the magnetism of an electromagnet somehow different in kind (principle, operation) than the magnetism of a permanent magnet? If not, then where does the energy flow come from in a permanent magnet?

 

I am very sorry if I am sounding obtuse here, but this simply does not made sense to me.

[Strange]

That is because of the resistance of the electromagnet: you need to supply energy to keep the current flowing. That energy is dissipated as heat. If you use a superconducting coil, then it requires almost no energy to maintain the magnetic field.

[StringJunky]

What

 

That is because of the resistance of the electromagnet: you need to supply energy to keep the current flowing. That energy is dissipated as heat. If you use a superconducting coil, then it requires almost no energy to maintain the magnetic field.

What's happening at the atomic level with the two types? What is it about magnetic materials, atomically, that keeps them that way vs electromagnets?

Edited March 8, 2016 by StringJunky

[swansont]

What

 

What's happening at the atomic level with the two types? What is it about magnetic materials, atomically, that keeps them that way vs electromagnets?

 

 

Permanent magnet elements have unpaired electrons, so their magnetic field contributions don't cancel, and they are in a solid with a physical structure that lets the fields add together.

[StringJunky]

 

 

Permanent magnet elements have unpaired electrons, so their magnetic field contributions don't cancel, and they are in a solid with a physical structure that lets the fields add together.

I forgot about the unpaired electrons. Cheers.