Learn the principles of magnetism and test them with a home-made compass

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Have you ever wondered how magnets work? Find out in this article and test the theory through experimentation.


Magnets are made up of clusters of iron atoms massively grouped together. While some clusters are magnetically oriented in one direction, other clusters point in the opposite direction. If you pour fine iron filings onto the surface of a magnet and observe them under a microscope, you can see how the filings cluster at one point. This specific point on the surface of the magnet is the boundary where the contrasting clusters meet.

When an iron object is exposed to the magnetic field of a magnet, the atomic configuration of the object aligns with the configuration of the magnetic field, which causes the object to be attracted to the magnet, now both objects are in a state of magnetism.

Planet Earth has its own magnetic field due to its iron core, Northern lights are a natural phenomenon produced by the Earth’s natural magnetic field; the geographic poles are defined by the Magnetic North Pole and the Magnetic South Pole.

magnetic field

A compass is a magnet that rotates on a pivot detecting the Earth’s natural magnetic field. We can discern North from South because of the magnetic attraction between the South Pole of the compass magnet and the Earth’s magnetic North Pole.

Now that we understand how magnetism works, let’s build a compass using a sewing needle, a small magnet, a cork and a container filled with water. We are going to do it in steps:

First step:

Magnetize one end of the needle by stroking it with the magnet for 2 minutes.

Second step:

We have to set the other end of the needle in the negative force. Turn the magnet over and repeat the first step on the other end of the needle.

Third step:

Cut the cork so that it is 1 to 2 cm thick.

Step 4:

Carefully insert the needle into the cork until the needle sticks out equally from each side.

Step 5:

Fill the container with a few inches of water.

That’s it!. Now we are ready to test our homemade compass. Place your device in the water and watch it move, it should line up so that it points North.

Extra fun:

Create a second compass and add it to the same bowl of water, what happens? What happens if you move the magnet closer to the water? What happens if you spin the compass?

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