An Electromagnet

An electromagnet starts with a battery (or some other source of power) and a wire. What a battery produces is electrons.

If you look at a battery, say at a normal D-cell from a flashlight, you can see that there are two ends, one marked plus (+) and the other marked minus (-). Electrons collect at the negative end of the battery, and, if you let them, they will gladly flow to the positive end. The way you "let them" flow is with a wire. If you attach a wire directly between the positive and negative terminals of a D-cell, three things will happen:

  1. Electrons will flow from the negative side of the battery to the positive side as fast as they can.
  2. The battery will drain fairly quickly (in a matter of several minutes). For that reason, it is generally not a good idea to connect the two terminals of a battery to one another directly. Normally, you connect some kind of load in the middle of the wire so the electrons can do useful work. The load might be a motor, a light bulb, a radio or whatever.
  3. A small magnetic field is generated in the wire. It is this small magnetic field that is the basis of an electromagnet.