How does the principle of induction apply to cooktops in electric ranges?
Some electric ranges have a coil of wire instead of a hot plate. This carries AC and produces a strongly varying magnetic field. When a conducting saucepan is placed upon it, eddy currents are induced in the metal in the base of the saucepan. These produce heat via ohmic losses (and hysteresis in magnetisation). One could consider the coil in the cooktop as a primary and the metal in the saucepan as the secondary of a transformer. As the heat is produced directly in the saucepan itself, less heat is wasted in the cooktop or the air. There is a further subtlety. Let’s compare a pot made from aluminium , which is non-magnetic but has low resistivity, with one made from iron, which is magnetic but has rather higher resistivity. If the two were placed in the same magnetic field varying in the same way, the Faraday emf would be the same. The ohmic power loss in the two would be given by V2/R, where V is the Faraday emf and R the resistance. R would be lower in the Al, so the ohmic power los
