Applied Science - Technology (3A)
Post Lab 

  • Discovering how machines operate using electricity.
  • Investigating how electricity is made.


  • alternating current
  • direct current
  • electricity
  • energy
  • worksheet
  • pinwheel template
  • 2 pipe cleaners
  • 1 straw
  • scissors
  • hole punch

Students discover how electricity flows through a city and make a model of a generator.



If a bulb "lights up," electricity is flowing through the wires in a closed circuit. If the bulb doesn't light up, electricity isn't flowing and it is an open circuit. Electricity can be generated by water (hydroelectric), batteries (chemical) or nuclear. Remember, electricity is a flow of electrons - it doesn't matter which "electrons" or what causes the energy that moves the electrons.

Electricity is all around us, but we rarely think about it. Students don't question where electricity comes from when a switch is turned on and off and many may not know where electricity originates. Many large cities get their power from hydroelectric sources. In the early 1900's, there was a "master" plan to develop and trap energy by damming water. The water would then move large turbines of a generator that could be converted to electricity. Generators have huge coils and giant magnets.  Generators can use water, wind, or other types of energy to move the giant magnets.  The spinning magnet  generates electrons and the coils capture them and creates current electricity. This electricity would then move to the cities by a network of wires.

The history of electricity is fascinating, especially because many of the early pioneers became famous. Prior to 1880's there was no public supply of power, even in advanced countries of the world. Sources had to be close and voltage had to be low because all that was first available was direct current. As the demands and distances of customers increased, alternating current was used because of its greater transmission through the use of transformers. It was slowly realized that electrical power was a common commodity and many public power stations started to develop a network to help generate a continuous source of power.

The first public DC power was in London in early 1882. The second was in New York in late 1882 and was started by Thomas Edison. In 1886, Westinghouse and Stanley created the first alternating current in Massachusetts. Students may be familiar with the Edison and Westinghouse companies that bear these early inventors names.

  1. Use the worksheet and see if students can visualize how these power plants carry electricity for all people to use. You may want to use this as an overhead and trace how electricity travels to an urban area.
  2. Students can use this diagram to try and find out who supplies power in your city. Ask them to discuss this with their parents or guardians to try and find the name. Make sure students realize that they pay for electricity that comes into their house. Have them identify whether they use electricity or gas at their home. Many home use both, some are all electricity.
  3. Generating electricity is difficult to understand.  Building a model generator helps students to understand the basic concepts.  Students need to make a cut out the pin wheel on the enclosed sheet. The pin wheel represents the turbines of a generator.  Sew one of the pipe cleaners in the center of the pin wheel and push it through the straw.  This would represent the turning magnet.   Coil another pin wheel around the straw, which represents the metal coils that would pick up electrons from the spinning magnet.   As the pin wheel turns it spins the magnet which produces electrons, that travel along the coil to be used by people. 

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