Steven Rowe, age 10, of Visalia, Calif., for his question:

HOW ARE MAGNETS MAGNETIZED?

Small magnets, such as the needle's of a compass, can be made by stroking the steel with each pole of a bar magnet in turn. But a more uniform magnetization can be obtained by placing the little magnets between the poles of a powerful electromagnet of horseshoe shape.

Long magnets can be put into a coil of wire and a powerful current sent through for a second or two. For large magnets, it is preferable to build them up out of many thin strips of steel of the shape required, each separately magnetized. By this method, the material becomes equally, magnetized throughout.