1. Electromagnetic Force Teaching Slides, 4.2
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Electromagnetic Force Course, 4.2: Electric Generators

2. Consider energy transfer
In the previous part of this investigation, what evidence did we see of energy transfer?
Do you think it’s possible to do the opposite, to transfer kinetic energy to generate electrical energy?
Electromagnetic Force Course, 4.2: Electric Generators
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3. 1.4.2 Electric Generators How can we generate electrical energy?
Electromagnetic Force Course, 4.2: Electric Generators
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4. Explore a generator
What evidence do you observe of energy besides kinetic energy in the system?
What energy transfers occurred to make the bulb light?
Electromagnetic Force Course, 4.2: Electric Generators
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5. Analyze generator components
Teacher master L, Hand-Crank Generator
Electromagnetic Force Course, 4.2: Electric Generators
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6. Observe other energy transfers
Notebook sheet 13, Energy Transfers
What energy transfers are happening to make the motor run?
Electromagnetic Force Course, 4.2: Electric Generators
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7. Compare generators and motors
Turn to “Generator Dissection” on page 72 of FOSS Science Resources.
Electromagnetic Force Course, 4.2: Electric Generators
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8. Compare generators and motors
Compare the energy transfers of a motor to the energy transfers of a generator.
Compare the inner components of a battery/motor system to the inner components of a hand-crank generator.
Electromagnetic Force Course, 4.2: Electric Generators
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9. Compare generators and motors
A motor and a generator can basically be considered the same component; it just depends on which way the energy transfers.
Electromagnetic Force Course, 4.2: Electric Generators
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10. View video Generator Dissection
Electromagnetic Force Course, 4.2: Electric Generators
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11. Generators and batteries
What do you think will happen when we hook up batteries to the wires of the hand-crank generator?
Can you make this an if, then, because hypothesis?
If not, use this: Based on what I know about how energy transfers, I think ____ because ____.
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12. Use the generator as a motor
What happened when you hooked up batteries to the hand-crank generator in class?
Electromagnetic Force Course, 4.2: Electric Generators
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13. Discuss electric cars What makes an electric car move?
Where does the energy come from to run an electric car?
Electromagnetic Force Course, 4.2: Electric Generators
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14. Discuss electric cars
Electromagnets, electric motors, and generators are technologies that make electric cars work. When you apply the brakes in a traditional car, the brake pads heat up as they rub against the wheels and apply friction to slow the car. The kinetic energy of the car transfers to heat energy, so it transfer to the environment. It is lost.
Electromagnetic Force Course, 4.2: Electric Generators

15. Discuss electric cars
In an electric car, this kinetic energy is not all lost. When you brake, the car’s electric motors can work as generators. These generators can transfer some of the kinetic energy to electrical energy, which is then stored as potential energy in the car’s battery. That battery can then be used to power the motor of the car. Engineers are always looking for ways like this to improve the energy efficiency of a car.
Electromagnetic Force Course, 4.2: Electric Generators

16. Discuss energy sources
Utility companies that provide electricity to people, homes, and businesses can’t create energy. They have to transfer some kind of energy to generate electricity, like the energy transfers in class with the hand-crank generator.
Electromagnetic Force Course, 4.2: Electric Generators
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17. Discuss energy sources
In many areas, the prime source of energy is chemical energy stored in fossil fuels such as coal or natural gas. Fossil fuels are nonrenewable, meaning that they were created by geological processes that take many millions of years. When they are all used up, other sources of electricity will become essential for us to have electricity.
Electromagnetic Force Course, 4.2: Electric Generators
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18. Examine real-life applications
Can you think of any real-life applications where environmental kinetic energy can be harnessed to generate electrical energy?
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19. Renewable energy
Energy from the wind blowing, water flowing, ocean waves, and steam from volcanic vents are examples of natural kinetic energy sources that can be harnessed to generate electricity. That electricity can power factories or homes and do anything you might typically want from a source of electricity. This is called renewable energy because the wind and water flow are not used up, they are constantly recurring.
Electromagnetic Force Course, 4.2: Electric Generators
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20. FOSS Science Resources
Read “The Rebirth of Electric Cars on page 47.
Electromagnetic Force Course, 4.2: Electric Generators
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21. FOSS Science Resources
Electromagnetic Force Course, 4.2: Electric Generators
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22. Focus on solar energy
Solar cells transfer light energy from the Sun into electrical energy.
Electromagnetic Force Course, 4.2: Electric Generators
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23. Model development
Connect a solar cell to a motor. Draw a diagram of the completed circuit in your science notebook. Develop a model by labeling the diagram to show the energy source and energy transfers.
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24. Environmental interactions
We can’t create energy or destroy it. we can only move it around by transferring it. Nonrenewable energy sources such as coal, natural gas, and oil will eventually be used up, and burning these fossil fuels affects Earth’s atmosphere and causes climate change.
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25. Environmental interactions
Scientists and engineers are eager to harness more renewable energy sources for human use.
Electromagnetic Force Course, 4.2: Electric Generators
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26. FOSS Science Resources
Read “Where We Get Energy?” on page 56.
Electromagnetic Force Course, 4.2: Electric Generators
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27. Review vocabulary
Spend a few minutes reviewing the vocabulary for this part. Update the vocabulary index and table of contents in your notebook.
fossil fuel
generator
nonrenewable
renewable
solar cell
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28. Answer the focus question
How can we generate electrical energy?
Electromagnetic Force Course, 4.2: Electric Generators
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29. Wrap-Up/Warm-Up
When a battery is connected to a bulb and the bulb lights up, does the energy get used up? Explain.
Electromagnetic Force Course, 4.2: Electric Generators
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30. All rights reserved. Copyright The Regents of the University of California.
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Photo credits:
Cover slide: © iStockphoto/Bosca78
Notebook image: © photastic/Shutterstock
Electromagnetic Force Course, 4.2: Electric Generators