CK-12 Physical Science - For Middle School

25.3. Generating and Using Electricity http://www.ck12.org

FIGURE 25.14

Whether a transformer increases or de-

creases voltage depends on the relative

number of turns of wire in the two coils.

FIGURE 25.15

Transformers play an important role in

supplying energy to the home. Why are

both step-up and step-down transformers

needed?

Lesson Summary

• A changing magnetic field produces an electric current in the process of electromagnetic induction. Current is
  generated whenever an electric conductor crosses magnetic field lines.


• An electric generator is a device that changes kinetic energy to electrical energy through electromagnetic
  induction. An electric transformer is a device that uses electromagnetic induction to change the voltage of
  electric current.


• Electric generators and transformers play critical roles in producing and regulating the electric current we
  depend on in our daily lives.

Lesson Review Questions

Recall

1. What is Faraday’s law?


2. Define electromagnetic induction.


3. Describe how an electric generator uses electromagnetic induction.