Science 9: Unit D – Electrical Principles and Technologies Topic 6: Generators and Motors

The History of Electromagnetism Electricity and magnetism are connected. You can use electricity to make magnets and you can use magnets to make electricity flow through wires. Using both electricity and magnets creates such things as electric motors which power electric cars, and electric generating plants which create huge amounts of energy. This connection was first discovered by Michael Faraday in the 1800s.

Using Electricity to make a Magnet We can make a magnet using wire, a source of electricity (eg. Battery/cell), and a piece of metal such as an iron nail. Magnets created this way are called electromagnets. 1. Hook up a wire to the negative end of the terminal on a battery. 2. Wrap the wire around the piece of iron so that it forms a coil. 3. Take the other end of the wire and hook it up to the other terminal of the battery. 4. Test out the electromagnet by bringing it close to pieces of metal such as paperclips. It should pick them up.

Electric Motors An electric motor is a device that takes in electrical energy and changes it to kinetic energy. Electric motors are used in many different things from toy cars to electric fans and can openers. An electric motor works through electromagnetism. An electric current is passed into a circuit. The circuit passes through a coil of wire making an electromagnet. When the electromagnet is activated by electricity it becomes a magnet and reacts with permanent magnets on the motor. The magnets repel each other and the motor begins to spin, electrical energy is now turned into moving energy.

Induction: Using Magnet to Make Electricity A moving magnet will generate an electric current in a nearby piece of metal wire. Also moving the wire in the presence of a magnet will cause the same effect.

Generators Generators work by taking in some kind of mechanical energy and changing and storing it as electrical energy. A generator basically works in reverse order from an electric motor. Moving energy is supplied which causes permanent magnets to move which cause an electric current to run through the wire.  A generator can either be used to supply electricity to a load (example: to a bicycle headlight) or to a battery to be stored for later use (battery chargers).

Power-Plants Use Generators on a GIGANTIC Scale A power-plant is basically a large generator with large, powerful magnets, and large coils of wire. To rotate the coils of wire (the turbines) a large mechanical force is needed. Different power-plants use different sources of mechanical energy to do this:

What are the Options for Electricity Generating Power-Plants? Fossil Fuel - Burning coal to produce steam energy – Alberta Wind turbines – Southern Alberta Hydroelectric (moving water moves turbines) – Mountains, Ontario anywhere where there’s waterfalls, fast moving water. Nuclear Power – Breaking up a small amount of uranium unleashes a large amount of heat which can be used to move steam turbines.

Homework 1. Compare and contrast electrical motors and generators. 2. Who first discovered that electricity and magnetism were connected. When? Explain the importance this discovery to our modern world. 3. What’s a magnetic domain? B) What types of materials have magnetic domains? C) How are magnetic domains aligned when the material is not magnetized? 4. Define and explain the term induction. 5. (p. 317: #2) 6. (p. 317: #5) 7. BLM 4-14