What materials do magnets attract?
As students can discover from simple experiments, magnets attract some, but not all, metallic objects.
Magnets attract two types of materials: those that are strongly magnetic (called ferromagnetic) and those that are weakly magnetic (called paramagnetic). They have no attraction for diamagnetic materials.
- The ferromagnetic materials are those that magnets are made of: iron, cobalt, nickel, and some less common elements. Steel is made from iron, so most forms of steel are ferromagnetic. Magnets strongly attract steel paperclips.
- The paramagnetic materials are those that magnets will attract to some degree, but at a much, much weaker level than ferromagnetic materials. Paramagnetic materials include aluminum and platinum.
- The diamagnetic materials are not attracted at all by magnets, and even repel them slightly. These include copper, lead, silver, wood, water, diamond, graphite, and living tissue. American coins such as the nickel, dime, and quarter are mostly copper, and are not attracted. (Some coins from Mexico, Europe, and Canada contain iron and are attracted.)
In the classroom, both paramagnetic and diamagnetic materials appear to be simply non-magnetic. Sensitive instruments are needed to tell the difference.
Did you know?
- A very strong kind of magnet called a rare-earth magnet will attract a dollar bill! The ink contains iron.