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Probably, each of us has played with magnets in childhood, but few children understood the way they work. But now you’ll learn interesting facts from the history of magnets and opens you something you haven’t known before. History and Definition Of Magnetism There’s connection between the laws of magnetism and the laws of electrical currents. The most significant terms here are generation and transmission of large amounts of electrical energy on an economical basis. A high-speed digital computer or the meter measuring the amount of electrical power should also be mentioned. Further you’ll learn some of the major principles of magnetism. Magnetism has been discovered long ago. The early Greeks were aware that some stones called lodestones, found in the district of Magnesia in Asia Minor, had the magic peculiarity and could attract small pieces of iron. It was the ore in these stones, Fe3O4, named magnetite for the region magnesia. Due to this any other substance that could attract pieces of iron was called a magnet, while attracted substances are known as magnetic substances. And the phenomenon connected with magnets and magnetic materials is called magnetism. It’s known that magnets can be man-made or artificial. It can be done by stroking a steel bar with one end of a lodestone or a magnet or by placing a steel bar in a coil of wire when an electric current is passed. Poles And Forces Between Them If iron pieces were splashed over a permanent magnet, the greatest concentration of them will appear near the ends of the magnet and you’ll see no pieces in the center. The regions at the ends of the bar are known as poles of the magnet, and the central line that joins the two poles is called the magnet's magnetic axis. If a bar is placed horizontally, it will line up in a north-south direction. Thus, one end of the bar magnet will be directed to the north, the pole seeking the magnetic north is known as the North Pole (N). The other pole seeking the magnetic south, is known as the South Pole (S). If you fixed bar magnets on pivots so that they were free to move, alike poles of two magnets would repel each other, while the opposite poles would attract each other. This discovery was first done by the French physicist Charles A. Coulomb in 1785. A magnetic field surrounds a bar magnet and penetrates it. Despite the fact that magnetic lines of force are impalpable, they possess such properties: 1. Magnetic lines never cross one another. 2. Alike poles push one another apart if they’re pushed towards each other. 3. Magnetic lines are continuous and create closed loops. 4. Magnetic lines are conducted by all materials. 5. Magnetic lines have a tension that shortens them. Thus, when two opposite poles are brought near each other, the lines of force between them are brought closer together. 6. Magnetic lines concentrate in magnetic materials. http://sellerby.com/good_15302_461438652-Caricature-Save-The-Date-Magnets.htm
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