Magnetism (Encyclopedia of Science)
Magnetism is a fundamental force of nature manifested by the attraction of certain materials for iron. Materials so attracted are said to be magnetic materials.
Humans have known about magnetism since at least 600 B.C. The force was almost certainly first observed in the attraction between the mineral known as lodestone, a form of magnetite, and pieces of iron. Englishman William Gilbert (1540603) was the first person to investigate the phenomenon of magnetism systematically using scientific methods. He also discovered that Earth is itself a weak magnet. Early theoretical investigations into the nature of Earth's magnetism were carried out by German physicist Carl Friedrich Gauss (1777855).
Some of the earliest quantitative studies of magnetic phenomena were initiated in the eighteenth century by French physicist Charles Coulomb (1736806). Coulomb found that the force between two magnetized objects is an inverse square law. That is, the force increases according to the magnetic strength of the two objects and decreases according to the square of the distance between them.
Danish physicist Hans Christian Oersted (1777851) first suggested a link between electricity and magnetism. Oersted found that an electric current always produces a magnetic field around itself. (A magnetic field is an area where a magnetic force is present.) Shortly thereafter,...
(The entire section is 1170 words.)
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Magnetism (Science Experiments)
Electricity can also produce magnetism
Electromagnets: Does the strength of an electromagnet increase with greater current
One of the most mysterious phenomena we witness every day is magnetismA fundamental force in nature caused by the motion of electrons in an atom., a fundamental force of nature caused by the motion of in an atom. You put a note on a refrigerator door. You watch the speedometer in a car tell you how fast you are travelling. You listen to a tape of recorded music. All of these depend on magnetism, but how do these things work? How does the simple physics of the magnet make so much possible?
What turns an ordinary piece of iron into a magnet? A large iron bar actually contains millions of "mini-magnets," small magnetized areas called . Each has a north pole and a south pole. If the poles of the iron's domains are aimed in all different directions, their magnetic forces act against one another and cancel each other out. When all of the domains are facing the same way, the bar becomes a magnet...
(The entire section is 3490 words.)