Mechanical Effects of Magnetization

—It was discovered by Joule that a bar of iron will increase ysg555 Of its original length when magnetized, and according to Bid well, it will contract again when highly magnetized. When rods are stretched by a weight, they contract more when magnetized, than do unstretched rods. Another mechanical effect of magnetization, is the faint metallic click heard when a bar is either magnetized or demagnetized Magnetism is accompanied by internal friction, as is evident by the heating of a bar when magnetized and demagnetized in rapid succe ion. Sir W. Grove showed that water containing finely divided magnetic oxide of iron, becomes clear on magnetizing in the direction of the magnetization, indicating that the particles of iron set themselves end-on, thus allowing more light to pa between them. A piece of iron awe twisted, tends to untwist on being powerfully magnetized.