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Science

Marvelous Magnets
by Elizabeth Klein

Over two thousand years ago, a black rock was found in a place called Magnesia, which is in modern Turkey. To the ancient Greeks who found the rock, it had magical qualities because it could attract some metals like iron and steel. It was a natural magnet and was later called magnetite.

Picture a traveller stumbling from the jungle holding up a small black rock on a piece of string. Odd, eh? But that's exactly what people did because when the magnetite stopped swinging, it always pointed in a north-south direction. The rock was also called a lodestone or "leading stone" because it helped to guide travellers on their journeys. The Chinese used magnets to assist them with travel as early as the 11th century. They placed a magnetic needle through a straw and floated it in a bowl of water. They had made a crude compass because the needle always pointed north and south and they were able to locate their way.

Today, magnets are still used for finding directions, but they have many other applications, too. Let's take a look at magnets.

Magnets come in various shapes and sizes. Long and narrow ones are called bar magnets, while curved shaped ones are called horseshoe magnets. Electromagnets are often flat on the bottom so that they can pick up large objects. They are created when an electric current passes through certain materials to make them act like magnets. Electromagnets can be turned on and off, so they are not permanent magnets.

All magnets have a north and south pole. If two similar poles are brought together, they repel each other. If opposite poles are brought together, they attract each other. Magnets have a region all around them that is called the magnetic field. This is an area where metal objects are affected by its force. The force is always strongest at the magnet's poles, although the rest of a magnet also exerts some force. The Earth itself has a north and south pole and its magnetic field influences almost everything around us, from the weather to our food.

Magnets are made from magnetic metals like iron and steel. The magnets in compass needles are used in modern orienteering. Once the needle stops spinning, it points to the Earth's north and south magnetic poles. Pilots of ships and airplanes rely on compasses to find their way. Magnets are also used in scrap yards as powerful electromagnets on cranes to move cars about. And in Japan, electromagnets cause "maglev" trains to float in the air. Maglev means "magnetic levitation" because magnetic repulsion moves them along steel tracks. These trains are fast and quiet and cause no pollution.

Did you know that magnets were used to treat pain and disease in many ancient cultures? When a permanent magnet or lodestone was placed on or near a person's body, it made them feel good. In Africa, magnetite was ground up and used in potions and foods. Natural magnets were used for health purposes by the Hebrews, Arabs, Indians and Egyptians.

We've come a long way since the ancient Greeks and Chinese studied the magnet's invisible force. Today, the beneficial effects of magnets have assisted scientists in the area of peoples' health and in producing a more efficient power source for the world's use.

Bibliography:

Fagan, Margaret. Hands on Science: Magnets to Dynamos. London: Aladdin Books Ltd, 1989.

Farndon, John. Science Investigations: Electricity. Lewes, East Sussex: White-Thomson Publishing Ltd, 2006.

Riley, Peter. Straightforward Science: Magnetism. London: Franklin Watts, 1998.

Rogers, Kirsteen, et. al. The Usborne Internet-Linked Library of Science: Sound and Electricity. London: Usborne Publishing Ltd, 2001.

Royston, Angela. My World of Science: Magnetic and Non-Magnetic. Oxford: Heinemann, 2003.

Photo: http://www.enasco.com/product/SB10287M

Elizabeth Klein has been a primary school teacher for nineteen years and is now a freelance writer. She lives in Sydney, Australia, with her husband..