Figure 1. Electromagnetic suspension: two views.

Magnetism is the phenomenon in which iron is attracted to a natural material called lodestone, the properties of which are similar to a magnet.

Metal filings form a magnetic field pattern around the poles of a magnet. (Corbis-Bettmann)

Lodestone and Magnets

Lodestone is a crystalline oxide of iron called magnetite. Until the 1800s, lodestones and the earth were the only sources of magnetism. Iron-based materials are attracted to a lodestone as well as to any other magnet. It is the attraction between a magnet and the iron in a refrigerator door that pins a photograph to the door. Bringing an iron-based material in contact with a magnet or lodestone will make a magnet of the material. Unfold a paperclip and rub it with a magnet. The clip becomes magnetized, with the magnetic properties concentrated near the ends of the...