Adding a 2nd Secondary coil & effects

[roro36]

Hi,
We have an induction heater, like a stove top one, not industrial.
I want to understand what happens when an additional load is added that it isn't intended to receive.
A plate goes on the induction warmer, it gets heated up, then removed and another plate takes it place.
What happens if the plates are stacked, i.e. 2 at a time, or 3 or more?
Surely, the induction will continue to all the plates, and what effect would this have on the current/power seen by the primary coil?
Depending on what feedback the machine uses to monitor the primary, if any at all, could the additional plates add extra impedance and force the primary to work harder, or does the impedance drop and create a higher current?
Thanks for any assistance.

 

[Baluncore]

Induction cooking involves using an AC magnetic field to induce eddy currents in the base of a conductive pan.
At the AC frequency used, the skin depth in the conductor will limit the depth of penetration and so shield thicker or multiple conductors.
The power to the induction oscillator will be regulated which will prevent overloading.