All motors may be considered in two broad categories; AC and DC, however most of the basic motor principles are the same. Magnetic fields are the basis for all electric motor operation. They produce the forces necessary for the motor to run. There are two basic magnet types: the permanent magnet and the electromagnet. The electromagnet has the advantage over the permanent magnet in that the magnetic field can be made stronger and the polarity can easily be reversed.
The construction of an electromagnet is simple, and is often part of high school science projects. A current flowing through a coil of wire produces a magnetic field. This magnetic field can be made stronger and can even be shaped to create unique motor operating characteristics by the way it is wound on an iron core. If the current supply was direct current, one end of the electromagnet is a north pole, while the other end is a south pole. These poles can be reversed by reversing the direction of current in the coil of wire, and that is exactly what happens 60 times a second in a single phase electromagnet.
