CK-12 Physical Science Concepts - For Middle School

http://www.ck12.org Chapter 5. Energy

FIGURE 5.189

Summary

• Electromagnetic devices are devices that contain electromagnets. Examples of electromagnetic devices in-
  clude doorbells and any devices that have electric motors, such as electric fans.


• The electromagnet in a doorbell attracts the clapper, which hits the bell and makes it ring.


• An electric motor is a device that uses an electromagnet to change electrical energy to kinetic energy. When
  current flows through the motor, the electromagnet rotates, causing a shaft to rotate as well. The rotating shaft
  moves other parts of the device.

Vocabulary

• electromagnet: Magnet created by electric current flowing through a coil of wire that is wrapped around a
  bar of iron or other ferromagnetic material.


• electric motor: Device that uses an electromagnet to change electrical energy to kinetic energy.

Explore More

Explore the electric motor animation at the following URL. Then describe two ways you can make the electromagnet
in the motor rotate more quickly. http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel_pre_2011/electrici
tyworld/thecostofelectricityrev1.shtml

Review

1. Describe an electromagnet.


2. What are some common devices that contain electromagnets?


3. Describe the role of the electromagnet in a doorbell.


4. What is an electric motor?


5. Explain how an electric motor turns the blades of an electric fan.