An induction burner consists of a ceramic plate with an electromagnetic coil beneath it. When you turn on the burner, an electric current runs through the coil, generating a fluctuating magnetic field, but no heat on the burner itself.However, once you set an iron or stainless steel pan on the burner, the magnetic field induces many smaller electric currents in the pan’s metal.
Iron is a poor conductor of electricity, so as all these small currents run through the iron, much of the energy is converted to heat. Thus, on an induction cooktop, the heat is coming not from the burner, but the pan itself. This can make for more efficient cooking–a pot of water will come to a boil on an induction stove in almost half the time of a standard gas stove. You’re also less likely to have hot spots in your pan, where food gets scorched because it has more contact with the heat source below. And, once you remove the pan, an induction cooktop cools off faster than a conventional burner, because it was only hot from contact with the pan.
The drawback is that only pans made from iron will work with induction stoves. Pans made of only copper or aluminum conduct electricity too well to generate significant heat. Cast-iron, stainless steel and pans made with layers of stainless steel all work. A rule of thumb-if a magnet will stick to it, you’re good to go.