Interaction of Forces


A solenoid creates a strong electromagnetic force.

How Are Electromagnets Used?

Electromagnets are used in items such as speakers, electric locks, and fuse boxes. The magnetism produced by an electric current is called electromagnetism. Electromagnetism can easily be turned on and off by connecting or disconnecting the power source. Electromagnetic strength can be controlled by increasing or decreasing an electric current. Another way electromagnetism can be increased is by making a solenoid. A solenoid is a coil of wire that acts like a magnet when a current passes through it.

Electromagnets are used in many different kinds of electric motors. An electric motor is a machine that uses electromagnets to change electrical energy into motion energy. A good example of this is a washing machine.

A washing machine motor takes advantage of some of the special properties of electromagnets. One of these properties is that the poles of an electromagnet can easily be switched back and forth from north to south. A washing machine has a regular magnet in the middle of the basin where you put your dirty clothes. It has electromagnets around the basin. Once it is turned on, the electromagnets around the basin switch back and forth from having north and south poles facing the middle magnet. The middle magnet becomes attracted and repelled to the outside electromagnets over and over again, causing it to spin. Electric motors can use electromagnets in many different ways to create motion.

Learn more about the properties of electromagnets. Click on the link below to watch a sample of the “Electromagnets” BrainPOP® movie. Answer the following questions in your science notebook as you watch the movie:

  1. Describe the shape of the magnetic field around a wire with a current running through it.
  2. How does increasing the electric current affect the strength of an electromagnet?
  3. Describe what a solenoid is and how it changes the electromagnetic strength of a wire.
  4. What three ways are electromagnets different than magnets?
  5. What do you notice about the polarity of the magnet in the middle of the electric motor animation? How does this affect its motion?

Mouse icon  Electromagnets

Click on the Show Answer button to check your answers.

Show Answer Answers:

  1. The magnetic field around a wire with current running through it is circular.
  2. An increased current will increase the strength of an electromagnet.
  3. A solenoid is a wire wrapped around an iron core. This shape magnifies the strength of the electromagnetism of the wire.
  4. Electromagnets can be turned on and off by connecting or disconnecting a power source. The electromagnetic force can be controlled by increasing or decreasing the current. Electromagnets can easily change the direction of the current from north to south.
  5. Every time it turns, a current runs through it and changes the north pole to the south pole and the south pole to the north pole. This causes the middle piece to spin because it is always being repelled from the magnets on either side of it.

Click on the link below to access the Real World Inquiry: Exploring Electromagnetism activity from the Interactive Digital Path website. Answer the two questions in this activity and check your answers.

Mouse icon Real World Inquiry: Exploring Electromagnetism