1. 17.3 Electric Motors and Generators

2. 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

3. 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.

4. 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.

5. 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.

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

7. 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: