First created in 1821, the homopolar motor was the first electric motor to be built. A homopolar motor is a direct current (DC) electric motor which produces constant circular motion. The great thing is that the homopolar motor is the simplest example of a motor possible. Plus it is really easy to experiment with. A homopolar motor can be made using a single AA battery, a single neodymium disc magnet, and a piece of copper wire.