What Are The Key Characteristics Of Magnetism?

A few experiments with two bar-shaped magnets will help us to see some fundamentals of magnetism. Lay a piece of paper over the first magnet and sprinkle some iron filings (such as those from a nail) onto the paper. Tapping the paper a few times with your finger will cause these filings to form a strange pattern. Notice that all the small pieces of iron assemble themselves in lines that seem to loop out of one end of the magnet and into the other. Here we are observing just a small part of the magnetic field. These invisible lines of magnetic force actually surround the magnet completely, in all directions. The areas on each end of the magnet where all these lines converge are called the poles. Every magnet has two poles that cannot be separated from each other. If we were to cut our bar magnet in half, the result would not be two half-magnets, each possessing one pole. Rather, we would have two complete magnets, each having two poles, as did the original magnet.

Now that we have traced the magnetic field and identified the two poles of the magnet, let's observe another very interesting property of magnetism. Tie a string around the middle of the magnet and suspend it in the air. You will notice that one end of the magnet will swing around until it points to the north. Move it away and it will always swing back to the north. The pole of the magnet that points to the north is called the north-seeking pole, and the one that points to the south, the south-seeking pole. This property of magnetism is the basis for the compass.