Magnets used in Motors
As mentioned in “Simple DC Motor #1” video all motors rely on the principles of magnetism. Magnetism is a force that attracts and repels metals. This is different than gravity. Gravity attracts all objects.
A magnet that is used as the fixed magnet on a motor has a magnetic pole at each end – one is called the south pole and one is called the north pole. As mentioned, like poles repel and opposite poles attract. For instance, a north pole of one magnet attracts the south pole of another magnet. Likewise, the north pole of that magnet repels the north pole of another magnet. The magnetic force around a magnet creates a magnetic field. This field is made up of invisible lines of force that run from the north pole to the south pole. When the opposite poles are brought together (north pole of one magnet to the south pole of another magnet), their lines of force tend to join, however, when like poles (north pole of one magnet and north pole of another) are brought together the invisible lines of force push each other away.
The principle of an electromagnet supports electric motors. These attractive and repulsive forces of electricity and magnetism were found to be related. Hans Christian Oersted found that a wire that has an electric current moving through it will produce an electric field. In addition, if you wrap a wire around a nail or an iron core and run current through it you will create a form of a magnet. This is called an electromagnet. Michael Faraday in his experimentation found out that if you move a wire through a magnetic field it will develop a current running through the wire. This principle is called induction.
Putting the two principles – magnetic and electric – into Motor Design
The above discoveries formed the basis for the invention of electric motors and electric generators. An electric motor turns electricity into motion. An electric generator turns motion (from a steam engine, or wind power, or a hand crank) into electricity. These two machines form the foundation of today’s electric power.