Magnetism: Magnetic Field and North Pole

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The ancient Greeks and Chinese basically discovered magnetism. What is magnetism? Magnetism is a force that acts at a distance to strongly attract iron, nickel and cobalt. The ancient Greeks and Chinese found out about some rare stones that attracted metal. They called these "lodestones." They discovered that with these lodestones, if they stroked a steel needle will point north and south. This was the beginning of the magnetic compass. The magnetic compass was used by Columbus when he crossed the Atlantic Ocean. Around 1600 William Gilbert found out that the Earth, itself was a giant magnet.

The three most commonly used metals for magnetism are iron, nickel, and cobalt. By combining, any of these one will get a permanent source of magnetism called a magnet. There are two types of magnets. Temporary magnets are magnets that are magnetized for a little while and then they stop. There magnetism ends. For example, a temporary magnet can be magnetizing a paper clip and then it will let it go, because the magnetic source is temporary. A permanent magnet is a little different. Permanent magnets are basically the opposite. They stay magnetized for a long period of time, sometimes up to five hundred years. These magnets are the normal ones that one would buy from a store or something. Temporary magnets are easy to magnetize and Permanent magnets are hard to magnetize.

Beyond the earth, lies the Earth's magnetosphere. The magnetosphere is filled with magnetic forces. These forces dominate the magnetosphere. Electric and magnetic forces determine its structure, instead of gravity like on earth. The truth is, "The Earth is a huge magnet, and its magnetic influence extends far into space."

Electromagnetism is another type of magnetism. By wrapping a bunch of electric coils around iron or any other magnetic metal, one can create a magnet. A lot of applications used today are based on electromagnetism, such as, door bells, telephones, loudspeakers, cassette recorders,...
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