Magnets and Electromagnets
Published by Devices like telephones, doorbells, televisions, and radios use magnets in order to operate. Those notes or receipts held by magnets on a refrigerator door are made possible due to the force created by magnets called magnetism.
Natural, Artificial, and Permanent Magnets
An unusual kind of stone that contains an iron ore called magnetite was discovered in the earth’s surface centuries ago. It attracted iron objects and when a long slender piece of this stone was hung by a string it always came to rest in a north-south position. Leading-stone was the name given to it or lodestone, rock-like and irregular in shape. They are regarded as natural magnets since they were mined from the earth’s surface.
Artificial magnets are those manufactured or made by man and mostly made of iron and steel. While some are made of alnico or a mixture of aluminum, cobalt, copper, and nickel. Usually, these magnets are named according to their shapes; magnets that are rectangular and cylindrical are called bar magnets.
Those that keep their magnetism for a long time are called permanent magnets and those that are made of soft iron are regarded as temporary magnets because they lose their magnetism easily.
Properties of Magnets
The ends of the magnets are called the south pole and the north pole and are marked with an S and an N. One can find out the properties of magnets by experimenting with two bar magnets and hang each one from a string.
Tie a string around the center of one bar magnet so that both sides of the magnet hang balance. Then let the magnet swing freely until it comes to rest in a north-south position. Bring the N pole of the second bar magnet near the N pole of the first magnet and observe what happens. Then bring the S pole of the second magnet near the S pole of the first magnet and find out what happens. Finally, hold the S pole of the second magnet near the N pole of the first magnet.
You would observe that the north and south poles attract each other while the north poles repel each other; in much the same way that both south poles also repel each other. This is always true in all kinds of magnets because they follow the law of magnetic attraction and repulsion, which explained that two unlike poles attract each other while the two like poles repel each other.
Poles are the strongest parts of a magnet and one can prove this by placing a bar magnet on a sheet of paper with paperclips. Try to pick up the magnet and observe where most of the paperclips cling.
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