Force between magnets

Magnets exert forces and torques on each other through the interaction of their magnetic fields. The forces of attraction and repulsion are a result of these interactions. The magnetic field of each magnet is due to microscopic currents of electrically charged electrons orbiting nuclei and the intrinsic magnetism of fundamental particles (such as electrons) that make up the material. Both of these are modeled quite well as tiny loops of current called magnetic dipoles that produce their own magnetic field and are affected by external magnetic fields. The most elementary force between magnets is the magnetic dipole–dipole interaction. If all magnetic dipoles for each magnet are known then the net force on both magnets can be determined by summing all the interactions between the dipoles of the first magnet and the dipoles of the second magnet.

It is often more convenient to model the force between two magnets as being due to forces between magnetic poles having magnetic charges spread over them. Positive and negative magnetic charge is always connected by a string of magnetized material; isolated magnetic charge does not exist. This model works well in predicting the forces between simple magnets where good models of how the magnetic charge is distributed are available.