A magnet is anything that creates a magnetic field, or exerts a force on ferromagnetic objects such as iron or other magnets. The Earth's magnetism comes from the large amount of liquid metal inside of the Earth's core.
A lodestone, containing iron, is a magnet that naturally occurs in nature. It was used in ancient China and Greece to calibrate compasses. Sailors discovered that when a piece of magnetic material is suspended from a thread, it always points north-south.
Permanent vs. Induced
Permanent magnets retain their charge forever, unless they are demagnetized. Induced magnets only become magnetized when they come in direct contact with a permanent magnet; they will lose their magnetism when no longer attached to a permanent magnet.
Hammering and heating a piece of metal in a north-south direction will align the atoms and magnetize the object. Rubbing a piece of ferromagnetic material in a north to south direction with another magnet can magnetize the object.
When the north pole of a magnet comes close to the north pole of another magnet, they will repel each other. When a north pole of a magnet comes into contact with the south pole of another magnet, they will attract each other.
When a magnet is heated in a hot flame, it will lose its magnetization because the molecules will become mixed up and no longer align in a north-to-south manner.
About the Author
Tommy Doc is a 2007 graduate of the University of Pennsylvania and an aspiring Internet entrepreneur. He was the sports editor for "The Pennsylvania Independent" while attaining his bachelor's degree in communications and environmental science. Doc is from Atlantic City, N.J. but has lived in Philadelphia, San Diego, New York and currently resides in Austin, Texas.
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