I am looking for a way to demonstrate that magnets adhere to the laws of thermodynamics, in particular the requirement that energy in a closed system be conserved.
To adhere to the requirement that energy not be lost, I would expect that the energy required to create a magnet would be offset by the energy exerted when that magnet exerts force.
My (elementary, if you will pardon the pun) understanding of magnets is that they exhibit a magnetic field because of a kind of polarization of the electrons, that looks something like this for a "perfectly" magnetized metal:
--------------------- --------------------- ---------------------
whereas an unmagnetized object would not have this polarization (if that is the right word), and might "look" something like this:
|\/-/-\|-/|\/-/-\|-/ /|--/-\|-/|\/-|\\|\- \-/-/-\-/|\/-|/-\|-\
The former object would exhibit the maximum force possible for the given material. The latter object would exhibit no magnetic force.
One would expect that the energy required to align the electrons would never exceed (but where inefficient it may be less than) the force that is exerted by the magnetic field.
As an example, suppose the polarization of a magnet from a completely unpolarized state uses 1 kJ of energy. To adhere to the laws of thermodynamics, the maximum amount of force the magnet can exert is 1 kJ, after which point it would be depolarized. One would expect the strength of the magnetic field to dissipate as it exerts force.
Is there a demonstration that one can perform to help visualize the conservation of energy by way of "charging" and "discharging" a magnet?