Any form of apparatus, having a rotating member, which generates, converts, transforms, or modifies electric power. Essentially all of the world's electric power is produced by rotating electrical generators, and about 70% of this energy is consumed in driving electric motors. Therefore, in a large sense, modern technology is built on the foundation of electric machinery. Electric machines are electromechanical energy converters; generators convert mechanical energy into electrical energy and motors convert electrical energy into mechanical energy. The basic laws of physics on which electric machinery is based were developed in the late nineteenth century.