Follow the Needle: Making a Compass
Every magnet has a north-seeking and south-seeking pole, just like the Earth, which is basically a giant magnet. If two magnets are brought together, the north pole of one will attract the south pole of the other. This is why compasses work on the Earth. The Earthís magnetic field is strong enough to make the north pole of a very light compass needle align with the magnetic south pole of the planet. If youíre confused (donít compasses point north???), you may not realize that the Earthís geographic North Pole is the opposite of its magnetic north pole! In other words, the planetís geographic North Pole is its magnetic south pole, and vice versa!
In this activity, you will make a magnet and see it respond to the bigger magnet that is our planet. We show you two ways to do this. Either way, it's important that there be no friction on the needle, so that it can respond to the slight tug of the Earth magnet.
What you need
- A bowl of water
- A paper clip or sewing needle
- A magnet
What you'll do
- Magnetize your paper clip or sewing needle by placing one end against the end of your magnet.
- Float the magnetized needle very carefully on the surface of the water. The end that you magnetized will point north or south, depending on how you magnetized it.
- If you are having a hard time doing this, try placing the needle inside of a drinking straw, on a piece of cork, or on anything that will help it float.
You can also make a simple compass with a piece of string and a bar magnet. Just hang a string from the top of a doorway and tie a bar magnet to the string so it is evenly balanced. As it turns, it will settle and point north-south. Learn more about compasses by playing with a virtual compass in a Java tutorial.
Did you know?
- A compass responds to the Earthís magnetic field. Scientists believe that field is generated by the churning of very hot liquid iron at the planetís core.
- The Earthís magnetic field does not run exactly from the North Pole to the South Pole, but is a little skewed. Thatís called the declination, and its effects, which vary depending on where you are on the planet, can be seen on compasses.
How far away from the Earth's geographic North Pole is its magnetic north pole?
Answer - 590 miles / 950 kilometers!
- 12 miles / 19 kilometers
- 50 miles / 80 kilometers
- 476 miles / 766 kilometers
- 590 miles / 950 kilometers
For more information contact Carlos Villa at firstname.lastname@example.org or (850) 644-7191.