Magnets and Magnetism

Most people think of magnets as toys with which children play for a few hours before discarding them for some other novelty, and magnetism as a subject of mathematical interest to scholars, but of no importance in everyday affairs; but all the electrical energy which is used commercially and in the household depends upon the existence of magnets, and its safe and continuous supply depends upon the proper operation of powerful electromagnets; the design of the elaborate,and expensive equipment for the production of electricity necessitates, therefore, a sound knowledge of the subject of magnetism. Until the underlying relationships between magnetism and electricity were first shown by such physicists as Oersted, Ampere and Faraday, electricity was only of scientific interest, and its utilization was not commercially practicable. Electricity is generated for commercial use by machines called dynamos; essentially, they are instruments in which wires are moved rapidly between the poles of powerful magnets; in the earliest types the magnets were permanent "horseshoe" magnets similar to those sold in toy shops-now very strong electromagnets are used, the electricity generated being passed through coils wound on, but insulated from, soft iron, so as to produce magnets of much greater strength than would otherwise exist