1. Simulation things to note…
Part A: your arrow tip = red part of needles
Part B: you can change battery voltage on the actual battery
Part C: circuit = what is on your screen, when you click on “polarity” = “flip polarity”
Voltage
Current
Resistance

2. Electric Motors and Generators
Chapter 17
Electric Motors and Generators

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

4. More Vocabulary Rotor – a piece that rotates in a motor
Commutator – a device that can reverse the flow of electric current

5. 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.

6. Electric motors
Around the edge of a rotor are several magnets, their alternating north and south poles facing out.

7. 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.

8. Electric motors
In a working electric motor, an electromagnet replaces the magnet you reversed with your fingers.
As the rotor spins, a commutator reverses the direction of the current in the electromagnet.

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

10. Battery Run Electric Motors
An electric motor that runs from batteries has the same three parts: rotating part, fixed magnets, and a commutator.
The permanent magnets are on the outside, and the electromagnets turn in the rotor.
Commutator
Permanent magnets

11. 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.

12. Exit Question!
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: