What is a magnet?

horseshoe magnet

A magnet is a object which has the property of attracting certain ferromagnetic materials such as iron and steel. If a magnet is suspended on a string or fine wire, it will turn until it aligns itself in a north-south direction.

Mankind has known about magnetism for centuries. There is evidence that the first natural magnets were found in a place in Asia Minor called Magnesia. These natural mag­nets consist of an oxide of iron called magnetite. When this ore is found in the magnetized state, it is given the name "lodestone," (leading stone). The properties of magnetite were first investigated by the English physician, William Gilbert, whose famous trea-tise "De Magnete" appeared around the year 1600.


Experiments show that magnetism is not distributed evenly over the surface of a magnet. If a bar magnet or piece of lodestone is dipped into a pile of iron filings, the filings will cling in large clusters near the ends of the magnet. These end points are called the poles of the magnet. If a magnet is suspended like a compass needle, the same end will always point in a northerly direction. This fact shows that the poles of the magnet are of two different types. This point is more clearly demonstrated if two like (such as both north) poles of magnets are brought together. The two like poles repel each other. If two unlike poles are brought together, there is a definite attraction between the two. Thus the familiar law is derived—like poles repel and unlike poles attract. In ordinary practice, the end of the magnet which seeks the north geographic pole is called a north pole, and the south-seeking end is called the south pole. They are also referred to as positive and negative poles.