Induction cooker is performed using direct induction heating of cooking vessels, rather than relying on indirect radiation, convection, or thermal conduction. Induction cooking allows high power and very rapid increases in temperature to be achieved, and changes in heat settings are instantaneous. In an induction cooker (“induction hob” or “induction stove”), a coil of copper wire is placed under the cooking pot and an alternating electric current is passed through it. The resulting oscillating magnetic field wirelessly induces an electrical current in the pot. This large eddy current flowing through the resistance of the pot results in resistive heating.
For nearly all models of induction cooktops, a cooking vessel must be made of, or contain, a ferrous metal such as cast iron or some stainless steel. The iron in the pot concentrates the current to produce heat in the metal. If the metal is too thin, or does not provide enough resistance to current flow, heating will not be effective. Most induction tops will not heat copper or aluminum vessels because the magnetic field cannot produce a concentrated current; “all-metal” induction tops use much higher frequencies to overcome that effect. Any vessel can be used if placed on a suitable metal disk which functions as a conventional hotplate.
Induction cooking has good electrical coupling between the pan and the coil and is thus quite efficient, which means it puts less waste heat into the kitchen, can be quickly turned on and off, and has safety advantages compared to gas stoves. Cooktops are also usually easy to clean because the cooktop itself does not get very hot.