Induction cooker

We found this on the bottom of a pan in a holiday home. Induction cookers are interesting. Alternating current in copper wires under a glass cooker top induce eddy currents in the bottom of the pan. This heats the pan. Articles suggest the need for ferro-magnetic pans but in the lab I often take pains to show induction in aluminium. Perhaps it is to increase the flux. It is said heat quickly. They were popular in student accommodation because the hob doesn't get hot so can't cause fires.