After this reading this section you will be able to do the following:
- Perform an experiment to detect what materials are magnetic and explain why you think they are magnetic.
After experimenting with the applet and thinking about the questions, please be sure to click on the discussion link.
- What conclusions can you make about these items and magnets?
- What is a magnet?
- How do you think something becomes a magnet?
- What do you think is different about the items that attract to a magnet and items that do not?
- How do you think magnets originated?
What is 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 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.
What is a magnet?
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.