Electric Motor (Encyclopedia of Science)
An electric motor is a device used to convert electrical energy to mechanical energy. Electric motors are extremely important in modern-day life. They are used in vacuum cleaners, dishwashers, computer printers, fax machines, video cassette recorders, machine tools, printing presses, automobiles, subway systems, sewage treatment plants, and water pumping stations, to mention only a few applications.
Principle of operation
The basic principle on which motors operate is Ampere's law. This law states that a wire carrying an electric current produces a magnetic field around itself. Imagine that current is flowing through
the wire loop shown in the figure below. The presence of that current creates a magnetic field around the wire. Since the loop itself has become a magnet, one side of it will be attracted to the north (N) pole of the surrounding magnet and the other side will be attracted to the south (S) pole of the magnet. The loop will begin to rotate, as shown by the arrow marked F.
AC motors. What happens next depends on the kind of electric current used...
(The entire section is 1300 words.)
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