Bar compass

Follow these instructions to make your own compass and learn about magnetic fields.

• 26 June 2006 | Updated 14 October 2011

• What you need
• What to do
• What's happening

Find north using a standard bar magnet in this activity.

What you need

To do this activity you will need the following items:

• a long bar magnet
• a ruler
• a piece of string
• some heavy books.

What to do

1. Wrap the string around the middle of the bar magnet and tie a knot.
2. Tie the other end of the string to one end of the ruler.
3. Place the other end of the ruler on the edge of a table and stack the heavy books on top of the ruler to hold it in place. The magnet should be able to swing freely and when it stops it should be facing north.

You have just created a simple compass.

What's happening

The Earth is a huge magnet with its own magnetic field. The field is strong enough to make another magnet turn if it is free to move. A magnet will always turn to point north.

Magnets have fascinated people for thousands of years. Around 1200 AD, Europeans discovered that a long, thin piece of magnetite always pointed north and south when hung on a string. Europeans used this as the first compass and gave the magnetite the special name lodestone, which means 'the stone that leads'.

Eager for more fun with magnets? Try the CSIRO Shop for the Busy Box Magnetics kit.