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 Question 699

 In plain English that a child can understand, how does a magnet work? — EK, Dale City, VA
There are several way in which objects in our universe can push or pull on one another and one of these ways is through electric or magnetic forces. Two objects that have electric charges are observed to push or pull on one another and two objects that have magnetic poles are also observed to push or pull on one another. That's simply the way our universe works. With electric forces, things are relatively easy—when you pull a sock and shirt out of the dryer, the sock may well stick to the shirt because friction has given the two different electric charges (one is positively charged and the other negatively charged). By playing around with electrically charged objects, you can convince yourself that (1) there are two different types of electric charge—normally called "positive" and "negative"—and (2) that like charges repel while opposite charges attract.

With magnetic forces, there is an annoying complication: magnetic poles (the magnetic equivalent of "charge") always come in equal but opposite pairs. As with electric charges, there are two types of magnetic poles—normally called "north" and "south"—and like poles repel while opposite poles attract. However, you won't be able to find a pure north pole anywhere; it always comes attached to a south pole (and vice versa). So any magnet you find will have at least one north pole and at least one south pole (while they typically have only one of each, they can also have many of each). The forces that these poles exert on one another are fundamental to our universe—I can't explain them in terms of more basic phenomena because they are already basic except at a very abstract level. (In fact, electric and magnetic forces are intimately related to one another and it is actually electric charges that are creating the magnetic poles that you observe in a magnet.) If you play around with several magnets for a while, you should be able to convince yourself about the existence of two different poles and that like poles repel while opposite poles attract. You should also notice that the magnets push one another directly toward or away from them (the forces between poles are parallel to the line separating them) and that the forces become stronger as the poles become nearer (the force is inversely proportional to the square of the distance separating the poles).

As for how a permanent magnet works, it's made from a material that contains ordered electrons. Electrons are intrinsically magnetic and, in a few special materials, that magnetism as organized so that the overall materials are themselves magnetic. Each electron has its own north and south pole, but together they give the material a giant north and south pole.