Magnetism





Magnetism has long been one of the great mysteries of the world. It has gone
for so long unexplained and although there has been a lot of progress in figuring out how magnetism works and what it’s caused by, it still isn’t completely understood. There are many theories about magnetism, but there is still much more yet to be discovered about magnetism. In the future it will probably be easily understood, but none the less intriguing.
Magnets have intrigued people for a long time; they were discovered long ago. Certain rocks and ores of iron called lodestones were found. These lodestones which were naturally magnetic rocks made of the mineral magnetite, were so mysterious to people that they caused many superstitions about themselves. One superstition was the belief that there were enormous lodestones rising out of the sea. Many sailors would not venture too far from land, believing that if they came too near one of these mountains the iron nails might be drawn out of their wooden ships. Another superstition about magnetism is an ancient Chinese legend that tells a tale about an Emperor Hwang-ti, who lived around 2600 BC. The story says that during a battle he was surrounded by thick fog. He managed to find his way through the thick fog by following a small pivoting figure with an outstretched arm attached to his chariot. The figure always pointed south because it had a loadstone embedded in its outstretched arm. Although it isn’t known if this story is true, most scholars agree that the first compasses were made by the Chinese. The fascination people have for the mysterious lodestone has continued for centuries.
The earliest investigators of magnetism regarded magnetic attraction as the main property of a magnet. They either ignored or were unaware of magnetic repulsion. Lucretius (99-55 BC), a roman poet and philosopher, was one of the first to observe that a loadstone or magnet stone could both attract and repel other magnets. For about thirteen hundred years after Lucretius, scholars insisted that certain magnets possessed the property of attraction while others possessed the property of repulsion. To their minds, it did not seem possible that the same magnet could both attract and repel other magnets. Gradually it became evident that the two ends, or poles of a magnet are unlike in certain respects. Roger Bacon (1210-1294), an English philosopher and scientist pointed out that magnets could repel as well as attract other magnets.
In 1600, William Gilbert, an English doctor, proposed that the earth was like a giant magnet. He had been experimenting with round pieces of magnetite and magnetized needles when he realized that the magnetite was attracting the needles in a way similar to the earth’s attraction of a compass needle. William Gilbert was also the first to call the ends of the magnets poles.
William Gilbert\'s idea that the earth is a giant magnet turned out to be basically true. The earth is thought to obtain its magnetism from electricity made by molten iron and nickel sliding around inside it. The Earth’s magnetism is centered at an area in northeastern Canada by the North Pole (another center is by the South Pole). The needle of a compass points not to the top of the earth but to the magnetic north pole off to the side. The ends of a magnet are named after the north and south poles of the earth. The actual words north and south are just handy names a scientist gave the different ends long ago so he could talk to people about them.
Scientist’s idea of what causes magnetism can best be explained by first saying that all things are made up of tiny particles called atoms. If you could look at the atoms in a piece of iron, which is what is used to make magnets, you would see that they are made up of even smaller particles. Atoms have a nucleus, which is made up of particles called protons and neutrons. Charged particles called electrons move around the nucleus. When electrons move they produce small magnetic fields. Usually electrons come in pairs. These pairs move in opposite directions and their magnetic fields cancel each other out. A piece of iron has a large number of unpaired electrons. In iron, the atoms align their