Point the Way

You know that Earth has both a north and a south pole. A very long time ago the Chinese discovered a way to use these poles to navigate. They found that if you put a rock called magnetite on a piece of wood and floated it in water, one end of the rock would always point to the North Star.

Sailors also used this tool, which we call a compass, to find their way while sailing on the oceans.

Today a compass needle is simply a thin, magnetized iron needle. The north point of a compass needle is attracted to the north pole and will always point north.

A compass is still a very useful and necessary tool for hikers, or anyone who needs to find his or her way. In fact, a compass played a very important part in the history of science.

You're the scientist!

Make a compass!

What do you think happens when a magnet is free to move in Earth's magnetic field? In this activity you will find out.

Materials:

• Bar magnet
• Yarn (about twice as long as the bar magnet)
• Scissors

Procedure:.

1. Cut a length of yarn or string about twice as long as the bar magnet.
2. Tie loops in both ends, and then put the bar magnet through both loops.
3. Find the balance point on this harness where the bar magnet hangs level, and tie a longer piece of yarn or string there.
4. Tie the other end of this string somewhere where the bar magnet can hang down and be left to swing on its own.

Analysis:

1. What do you think will happen to the magnet? Write your hypothesis down.
2. Observe the magnet. What happens? Record the results below.
3. Can you explain what happened? Is the end of the magnet labeled "N" the north pole of the magnet? Explain your answer.