How to make a simple compass
Use a magnet, a needle and a cork to track north and south
1. Rub the needle
First, you will need to find a bar magnet and a sewing needle. Now hold the needle by the eye – where the hole is – and rub the north end of the bar magnet along the length of the needle. Lift the magnet away from the needle, then move it to the other end and rub it again. You will need to repeat this process 50 times to ensure your needle is correctly charged.
By rubbing the magnet along the needle you are moving the charged particles inside the metal, called electrons. Normally they all point in different directions, so the metal of the needle doesn’t have a magnetic pull in any particular direction. However, when you rub the magnet along the needle the particles all line up, creating a charge in one direction.
3. Stick it on
In order to create your compass, you need to place your needle in a place that will be able to turn freely, without friction stopping it moving. The easiest way to do this is to place your needle in water – but you need it to float! To make it float, put some sticky tack on the top of a cork and stick the needle into the tack so that it’s balanced on the top.
4. Get it floating
Run some water into a bowl and let it settle for a few minutes. Any small movements in the water might cause the cork to move, so you want the water to be as calm as possible. When the water is calm, carefully place the cork in the centre of the bowl so that the needle is on top and can move freely. If it starts moving towards the edge of the bowl, stop it with your finger.
5. North and south
Wait a moment and the cork and needle should start to move – you might have to wait a little while for the needle to settle. The eye of the needle should end up pointing north, while the sharp part of the needle will point south. This works because of the magnetic field created by the metals in the Earth, which affect all kinds of magnetic objects.
Magnets create magnetic fields, and these show the pulling power that the magnet has. The Earth’s molten metallic core means the planet is like a huge bar magnet, so when you charge a needle like this, it lines up with the magnetic field of the Earth and points north. That’s why people can use compasses to navigate!
For more science and technology articles, pick up the latest copy of How It Works from all good retailers or from our website now. If you have a tablet or smartphone, you can also download the digital version onto your iOS or Android device. To make sure you never miss an issue of How It Works magazine, subscribe today!