If a permanent magnet is moved into the center of a coil shaped conductor and then pulled out, a magnetic field changes and a current flows in the conductor. This is called electromagnetic induction.
The high-frequency induction heating utilizes this electromagnetic induction. AC current flows in the coil instead of using a permanent magnet to generate alternate magnetic flux so that an induced current (eddy current) flows in the heated object. This induced current generates joule heat through eddy-current core loss, and the heating by using heat generated in this way is called induction heating. Here, the eddy current induction is centered at the part of the object which is closely located to the coil while the induction current is strong around the object's surface and weak at its inside.
As the energy can be concentrated at the heated object's required part and thus efficient rapid heating is possible, the productivity and workability are improved.