Magnets have two poles, with magnetic force concentrated at the ends. The Earth also has magnetic poles, which a compass responds to. A magnet will always align with the Earth’s magnetic poles. The first compass was mentioned by ancient Chinese. Theories suggest tiny magnetized molecules or electrons create magnetic fields in materials.
In a magnet, the magnetic force is concentrated at the ends and weakens in the middle. These magnetically strong ends are called magnetic poles. Magnets have two poles, both of equal strength. The Earth also has magnetic poles. A compass works because the magnet in the compass responds to the magnetic force of the Earth.
A simple bar magnet left to spin freely will always align with the north and south magnetic poles of the Earth. Some magnets are marked with an N on one end and an S on the other. This is because the N end will always point north, while the S end will always point south. If two magnets are placed side by side, the N end of the first magnet will attract the S end of the second, while the N ends repel each other.
The pull of the Earth’s magnetic poles is so strong that a magnet will always align with the poles, no matter how far away it is from them. It should be noted that the Earth’s magnetic north pole does not align perfectly with the geographic north pole. Magnetic north is actually about 15 degrees away from true north.
For thousands of years, people have used the Earth’s magnetic poles to help navigate them. A compass is basically a freely rotating needle. Since the needle is magnetized, it will always point north. By knowing which direction is north, explorers and travelers can figure out which way they are going. The first mention of the compass was made by the ancient Chinese around 210 BC
There are a couple of different theories as to why magnets behave the way they do. The older of the two is Weber’s theory. He claims that magnetic substances are made of tiny magnetized molecules. When left alone, these molecules point in all different directions. If a magnet is pulled across the material multiple times moving in the same direction, the molecules will line up as a series of tiny magnets from the north end to the south end, creating magnetic poles at both ends of the metal.
A similar but more sophisticated theory is based on the knowledge that electrons have a magnetic field. Electrons are the tiny units that orbit around atoms. Every atom has at least one electron. Domination theory states that if an atom’s electrons all orbit in different directions, their magnetic fields will cancel each other out. If, however, they orbit in the same direction, the atom will be magnetised. A material filled with these magnetized atoms is a magnet.
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