Principle of Induction Heating
As shown in Fig. 1 on the right, when the metal to be heated is inserted into the heating coil in which an alternating current (high-frequency current) is passed through, alternating magnetic flux (magnetic lines of force) is thus generated.
As shown in Fig. 2 on the right, high-frequency current is caused by the skin effect of metal, and current concentrates on the surface of the metal when the frequency is high. The lower the frequency, the deeper the penetration into the metal.
