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.

How to Make your Own Magnet

By magnetizing a piece of an unmagnetized iron like an ordinary nail – you can make your own magnet. Try to hold a nail with the point out. Stroke the nail with the N pole of a magnet. Then do this using the same pole of the magnet all the time for at least 25-45 times. Bring the nail near the paperclips or thumbtacks and observe what happens. Take the paperclips away from the nail and pick them up again using the same nail after one or two minutes. Nails made of soft iron can easily be magnetized but lose magnetism easily.

You may also want to try this experiment using thumbtacks or paperclips, about 35 centimeter long of a piece of wire, an iron nail (about 5 inches), and a dry cell (an ordinary 3V battery). Wind the middle third of the wire around the nail at least 20 times, wound tightly without any criss-crossed. Then connect the two ends of the wire to the terminals of the dry cell (the negative and positive sides of the cell) so electric current would flow through the wire. Bring the wire-wrapped nail over the thumbtacks or paperclips and observe what happens. After a few minutes, disconnect the wire from the dry cell.

Taking Care of Magnets

Magnetism can easily be destroyed when dropped repeatedly to the ground, by knocking it repeatedly with a hard object such as hammer, or by heating it. Therefore to protect its magnetism, avoid heating a magnet or placing it near a fire. Avoid knocking it with a hard object or dropping the magnet on the floor. Store magnets properly by protecting with magnetic keepers right across their poles while bar magnets should be stored in a way that north pole of one magnet is beside the south pole of the other.

Electromagnets

This is the most useful kind of temporary magnet and was made by passing an electric current through a covered wire that have been coiled around a soft iron bar. It was Hans Christian Oersted, a Danish physicist who first discovered how electromagnets work and it led to the invention of generator and electric motor.

Electromagnets are used in motors of electrical appliances like electric fans, doorbells, telephones, washing machines, and transformers. Electromagnets are also attached to cranes to attract and move heavy loads of steel bars and scrap iron from one place to another. It is also used for separating magnetic substances from non-magnetic substances. Electromagnets made telecommunications possible.

In the medical field, electromagnets are important since they are used to remove foreign bodies such as iron nails and other magnetic substances from a patient’s body. The force or strength of attraction of an electromagnet can become stronger by increasing the number of dry cells or by increasing the number of turns in a coil.

Magnets and electromagnets have many uses and both should be given proper value and care.