Electric motors
February 10, 2010
Electric motors are everywhere! In your house, almost every mechanical movement that you see around you is caused by an AC or DC electric motor. By understanding how a motor works you can learn a lot about magnets, electromagnets and electricity in general. On this page we hope you will learn what makes an electric motor spin.
An electric motor is all about magnets and magnetism. A motor uses magnets to create motion. If you have ever played with magnets you know the law of magnets: Opposites poles attract and like poles repel. So if you have two bar magnets with their ends marked "north" and "south," then the north end of one magnet will attract the south end of the other. On the other hand, the north end of one magnet will repel the north end of the other. Inside an electric motor, these attracting and repelling forces create rotational motion.
The armature (or rotor) is an electromagnet. Like the Beakman rotor above made of copper wound in a circle, the motor below has copper wound around a soft iron core. The field magnet is still a permanent magnet, only this time there are two semi-circular magnets fitted inside a steel casing. In some larger motors and generators the field magnet could also be an electromagnet. In smaller motors it usually isn't to save the electricity that would otherwise be needed to make magnetism and also to reduce complexity. Actually, these days there are quite a few large motorsusing magnets to drive cars and the like. The Solar Navigator catamaran uses permanent magnet motors that are very efficient.
Posted by Wisansaya Meepojana. Posted In : Science
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