Some of this thread has gotten to some of the basics relating to magnetism, which is a bit of a mystery to me. There's the dynamic magnetism that arises through a moving current. And there's the static magnetism that is created through the formation of magnetic domains in a ferromagnetic material, in which the spins of the atoms are aligned in one or another direction. At a high level, these concepts make sense to me.
What I don't fully understand is how conservation of energy applies in the case of the system in this photo: http://i.imgur.com/YzC8KlI.jpg Here we have a strong permanent magnet and a keyring. They are configured in an arrangement that, without the influence of the permanent magnetism, would be unstable against the force of gravity. But the magnetism of the magnet keeps the two components together in the assembly against gravity. A common explanation for this kind of thing will be something to the effect that no work is being done in this system because there is no movement. But I think that oversimplifies the mystery of it. We can suspect that work is in fact being done at the atomic level if in our minds we replace the permanent magnet with a magnet formed from a current carrying wire wrapped around a piece of metal. We can set up a magnetic field in this system by keeping current flowing through the wire, and we must keep the current flowing in order to continue to have the field. We could do that by turning a crank on a small hand generator or burning petroleum to power an electrical generator. With the permanent magnet, one suspects that there must be something comparable going on as well. My question is -- what is it that seems to be adding energy to the system in order to keep the permanent magnetic field in place, analogous to the motor with the crank or the electrical generator? What is the fuel in this system that does the work? Eric
