In an induction cooker, a coil of copper wire is placed underneath the cooking pot. An alternating electric current flows through the coil, which produces an oscillating magnetic field. This field induces an electric current in the pot. Current flowing in the metal pot produces resistive heating which heats the food.
I need to get me some cast iron (ok maybe not, I can barely lift the ones we have back home) or magnetic stainless steel pots/pans!