Conducting sphere in alternating magnetic fields

The field disturbance produced by a conducting metallic body in an alternating magnetic field is of interest from several points of view, for instance in connection with eddy-current losses, induction heating, and in high-speed rotation of a sphere induced by a revolving field. Again, the location of a hidden metallic body, a problem met in a number of industries, is often carried out by producing an alternating magnetic field and detecting the presence of the body from the field distrubance produced by it.