On the surface, Induction hobs are made from toughened glass that is generally around 6mm thick for commercial hobs which are heavier duty than the domestic ones available. Inside the hob is a copper wire coil which electric current passes through, causing a magnetic field which induces an electric current in the cooking pan/pot, causing it to heat up. The cooking pan or pot must be made from or contain ferrous metals making it magnetic, otherwise they will not heat up.