World's simplest motor
By Clarence Klassen
Today’s topic is a simple one. You get a chance to build a working motor with three parts – magnet, battery, and wire. I have attached a diagram. Search for the magnet as “3/4-in. rare-earth magnet." You should have no trouble with the AA battery and wire.
A few words of caution. This contains small parts. Keep away from small children. Swallowing a rare-earth magnet could be very dangerous – considering that the person who swallows the magnet possibly swallowed something else magnetic the day before.
The magnets are very strong and may pinch.
The motor runs hot. Do not operate on the family dining-room table.
This motor type is a homopolar motor. The magnetic flux lines are always cut in the same direction so no commutator is required. A slip ring is required.