An alternating current passing through a copper coil induces a magnetic field around the coil per Faraday ‘s Law of Induction. A piece of metal placed within that oscillating magnetic field will experience the opposite effect as an electric current is induced within the metal. These eddy currents passing through the metal induce an opposing magnetic field around the piece of metal and cause it to heat up through a process known as Joule heating. The stronger the change in magnetic field, the more heat generation.
When a piece of aluminum is placed within a magnetic field generated using a 1.6 kW power inverter operating at 204 kHz, it rapidly heats and eventually melts at 660 °C. The molten aluminum reaches a final temperature of 1,200 °C before the current is finally shut off.