CK-12 Physical Science Concepts - For Middle School

(Marvins-Underground-K-12) #1

5.91. Electric Transformers http://www.ck12.org


FIGURE 5.196


Q:Both step-up and step-down transformers are used in the electrical grid that carries electricity from a power plant
to your home. Where in the grid do you think step-down transformers might be used?


A:One place that step-down transformers are used is on the electric poles that supply current to homes. They reduce
the voltage of the electric current before it enters home circuits.


Summary



  • An electric transformer is a device that uses electromagnetic induction to change the voltage of an electric
    current.

  • A step-up transformer increases voltage. A step-down transformer decreases voltage.


Vocabulary



  • electric transformer: Device that uses electromagnetic induction to change the voltage of electric current.


Explore More


Explore the electric transformer simulation at the following URL. Then answer the questions below. http://phet.colo
rado.edu/en/simulation/generator



  1. Explain what you have to do to light the light bulb when you use direct current (DC) in the electromagnet.

  2. If you use direct current in the electromagnet, which type of current flows through the pickup coil? How can
    you tell?

  3. If you decrease the voltage of the direct current, how does the voltage of the pickup current change?

  4. How does the number of loops in the pickup coil affect the voltage in that circuit?


Review



  1. What is an electric transformer?

  2. How does an electric transformer use electromagnetic induction?

  3. Compare and contrast step-up and step-down transformers.

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