|Physical Science||Transformation of Energy 6C1.00||Science In Society||Societal Needs 4.4 bc|
CONTENT STANDARD: Physical Science
CONTENT TOPIC: Transformation of Energy
CONCEPT: Various sources of energy can be utilized in the production of electricity.
CONTENT OBJECTIVE: 6C1.00 To understand various methods of producing electricity
INSTRUCTIONAL OBJECTIVES: The learner will:
TN COMPONENT OF SCIENCE: Science In Society
BENCHMARK: Needs and wants fuel scientific development.
4.4c Science and Technology may produce changes that affect society and groups within societies.
BENCHMARK: The global environment is affected by national policies relating to science and technology.
Electrical energy is of limited use to us unless we have ways to convert it to beneficial forms of energy. Household appliances are devices that convert electrical energy to useful energy. The electrical energy might have been produced by heat, light, nuclear, chemical, or mechanical energy.
Chemical energy can be used to produce electrical energy by using the wet cell, dry cell, and storage battery. Chemical energy is stored in molecules of matter. Chemical energy is stored energy that is given off when some molecules of matter react with each other. The wet cell, dry cell, and storage battery are examples of stored chemical energy.
Mechanical energy can be changed to electrical energy. This energy is produced through an electric generator. Nearly all the electric energy used today is produced by electric generators. Most of the energy used to operate electric generators comes from turbines. The turbine is turned by mechanical energy. Moving water is an example of mechanical energy. The principles in all generators are the same: there are coils of wire rotating in magnetic fields, and in the electric generator, mechanical energy is changed to electric energy.
Light energy can be used to produce electrical energy by using the photoelectric cell and the solar battery. When light shines on certain materials, an electric current is produced. This is called the PHOTOELECTRIC EFFECT on light energy. An example of this energy is seen when you walk up to a door that is operated by an "electric eye." The door opens when you cross the beam of light.
Solar cells produce electricity directly from sunlight. Solar cells are made of a material called silicon which, when hit by a ray of light, gives off electrons. As long as light keeps hitting the silicon, an electric current is sent out.
Heat energy can be changed to an electric current by a method called the thermoelectric effect. To create this effect, a thermocouple is used to generate electricity as a result of differences in temperature. This type of energy is used in automobiles. The current produced by this method operates a gauge that shows engine temperature.
Nuclear energy produces electricity when tiny particles of matter are split apart. The heat from this reaction can be used to change water into steam. The steam can then turn turbines to produce electricity.
1. Hair dryer
4. Electric car
5. Food blender
Ask students to discuss how these electrical devices work and what energy conversions occur in each device.)
(Demonstrate how electrical energy is changed to electrical by turning the handle on the hand-held generator and demonstrating how the light works.
Connect a zinc strip to a copper strip with alligator clips and wire. Immerse each strip in the lemon. Check voltage with a voltmeter.) Class, how does this experiment show how electrical energy is made from chemicals?
1. Why do you think that our government has national policies related to electricity?
2. What needs do you have that demand electricity?
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