Raymond Guinn, age 74, of Farmersville, Calif., for his question:

HOW DOES AN ELECTROMAGNET WORK?

An electromagnet is a temporary magnet formed when electric current flows through a wire or other conductor. Most electromagnets are made up of wire wound around an iron core. This core is made from magnetically soft iron that loses its magnetism quickly when the electric current stops flowing through the wire.

Electromagnets are used to operate electric doorbells, buzzers and relays. Powerful industrial electromagnets are used to lift heavy pieces of scrap iron and even to guide atomic particles along the desired path inside particle accelerators.

A Danish physicist named Hans Oersted discovered in 1820 that an electric current produces a magnetic field. The first practical electromagnet was built in 1827 by an American physicist named Joseph Henry.