Heating principle of electromagnetic roaster from Paul

When a loop current is applied, the effect is equivalent to that of a magnet bar.

Therefore, there is the generation of n-S pole of magnetic field on the coil surface, i.e., the magnetic flux passing through.

If alternating current is used, the magnetic poles of the coil and the magnetic flux across the circuit will change.

When a magnetic metal surface is placed above the loop coil, current is induced on the metal surface.

Because there is resistance on the metal surface, the induced current causes the metal surface to produce heat energy, which is used to cook food.

The larger the current, the higher the heat generated and the shorter the cooking time.

The greater the induced current, the greater the flux change across the metal surface and, of course, the stronger the magnetic field.

As a result, the coils that used to be powered by alternating current need to be wound together with more turns.