# Electromagnets

### After reading this section you will be able to do the following:

• Discuss the relationship between electricity and magnetism that is demonstrated.
• Discuss what happens to the electromagnet when the current is reversed.

## How can electricity be used to make a magnet?

In this experiment you used electricity to make a temporary magnet, called an electromagnet. As long as the electric current was on, the iron crane was a magnet and could pick up ferromagnetic objects. When the electricity was turned off, the magnetizing cause was no longer present, so the object was not attracted to the iron crane. So, let's see how electricity is able to make a magnet.

## Magnetism and Current Flow Direction

In the experiment above, you saw how magnetism makes it possible to convert mechanical energy into electrical energy, allowing electric generators to make electricity. In the experiment above and the experiment below, we see that magnetism can also let us do the opposite; that is, we can convert electricity into mechanical energy. In the experiment you just finished, when you turn the current on, the current flows through the wire and temporarily magnetizes the bar of iron material. One end of the magnet becomes a north pole and the other end becomes the south pole.

When you reverse the direction of the current flowing in the wire, the north and south poles are also reversed. When you reverse the current again, the north and south poles reverse again. In fact, each time the current is reversed, the north and south poles will exchange places. Direct current (DC) flows in only one direction through a wire. So, in order to change the direction of flow change, there needs to be a reversing switch. As you will see in the next page, alternating current (AC), on the other hand, is constantly changing its direction of flow, so a reversing switch is not necessary.

### Review:

1. Electromagnets are temporty magnets.
2. When the direction of the current flowing in the wire of an electromagnet is reversed, the north and south poles of the electromagnet are also reversed.