Magnetic Behavior

Magnetism

Just like when the Greeks of the old times discovered the first naturally occurring magnetic stones, or natural magnets, you have been observing a property of matter called magnetism. Magnetism is the force of attraction or repulsion in and around a material. Magnetism is present is all materials, but in some materials it is at such low levels that it is not easily detected.  Certain materials such as magnetite, iron, steel, nickel, cobalt and alloys of rare earth elements, exhibit magnetism at levels that are easily detectable.

Magnets

Magnets are very common items in the workplace and household. Uses of magnets range from holding pictures on the refrigerator to causing torque in electric motors. A magnet is any piece of material that has the property of attracting iron (or steel). Magnetite, also known as lodestone, is a naturally occurring rock that is a magnet. This natural magnet was first discovered in a region known as magnesia and was named after the area in which it was discovered. Magnetism may be naturally present in a material or the material may be artificially magnetized by various methods. Magnets may be permanent or temporary. After being magnetized, a permanent magnet will retain the properties of magnetism indefinitely. A temporary magnet is a magnet made of soft iron, that is usually easy to magnetize; however, temporary magnets lose most of their magnetic properties when the magnetizing cause is discontinued. Permanent magnets are usually more difficult to magnetize, but they remain magnetized. Materials which can be magnetized are called ferromagnetic materials. We will talk more about making a magnet later on.

The applet below demonstrates magnetism in action: a magnet moves over various objects and magnetism attacts some of them to the magnet. 

What Happens when you cut a magnet?

A magnet can be cut into smaller and smaller pieces indefinitely, and each piece will still act as a small magnet. Thus, the cause of magnetism must be from a property of the smallest particles of the material, the atoms. So what is it about the atoms of magnets, or objects that can be magnetized (ferromagnetic materials), that is different from the atoms of other material? For example, why is it that copper keys or aluminum soda cans cannot be magnetized? These questions will be explored in the upcoming pages.