17.3 Electric Motors and Generators

Electric Motors and Generators Electrical energy: energy from moving electrical charge Mechanical energy: energy due to motion or position Motors: electrical energy to mechanical energy Generators: mechanical energy to electrical energy

Electric motors Motors have three parts: A rotor with magnets that alternate. One or more fixed magnets around the rotor. A commutator that switches the direction of current to keep the rotor spinning.

The disk is a “rotor” because it rotates. Electric motors To make the rotor spin, bring a permanent magnet close to its edge. The free magnet attracts one of the magnets in the disk and repels the next one. The disk is a “rotor” because it rotates.

Generating Electricity A generator converts mechanical energy into electrical energy using the law of induction. As long as the disk is spinning, there is a changing magnetic field through the coil and electric current is created.

Electromagnetic Induction Electromagnetic induction: a moving magnet produces a current in a coil of wire Generators use electromagnetic induction to create electricity

Check! The diagram below represents the rotor of an electric motor. To cause the rotor to turn in a counter-clockwise direction, the north pole of a magnet should be placed at position: