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When most of think of a motor, we think of a gas-powered engine in a car. But electric motors are much more common than most of us may realize. They are, in fact, much more prevalent than even gas-powered motors. Simply, an electric motor converts electrical energy from an AC (alternating current) or DC (direct current) source to mechanical energy. Every motor in our homes, therefore, is usually an electric motor, whether it is the fan motor inside a computer, the compressor in the refrigerator, the motor that drives the VCR or the miniature motor in an electronic toothbrush.

An electric motor typically uses magnets to convert electricity to motion. These magnets include permanent or electro magnets, or a combination of both. A typical electric motor uses a rotor placed between stationary magnets with fixed poles. When electricity is sent through the coils wrapped around the rotor, it gains a magnetic field. This field causes it to turn, attempting to align its poles with the stationary magnets around it. When it reaches a certain position, the electric charge is reverse. This causes the rotor to continue its circular motion to align with the opposite side. Once it reaches the next position, its charge again changes, and its circular motion continues until the power is shut off. Each time the rotor spins, it generates mechanical energy. The rest of the motor directs this energy to the proper source, whether it is causing a fan to spin or turning a wheel. Most motors use three poles rather than two in order to minimize shorts and enhance balance. It also prevents the rotor from becoming stuck in a horizontal position between two opposite poles.

Rotary motors, however, are not the only type of electric motor. Other electric motors, such as a stepper motor, use the fixed magnets within the rotor. These motors send the electric charge cascading through the outer coils, thereby driving the motor. Most AC motors also operate using this principle, generally incorporating a three-phase design to create a rotating magnetic field. Induction and synchronous AC motors both use a three phase design.

Additional electric motor types are brushless DC motors, used for fans and other spinning devices; linear motors, which apply the same principles as a rotary motor across a linear plane (such as a monorail traveling in a single direction); and universal motors, which can be powered by AC or DC current. The applications of electric motors are extensive, and horse power outputs can range from minute amounts to continuous, high levels.