Grace Andrews from Christchurch asks :-
How does induction heating on a stove work?
Pat Bodger, an electrical engineer at the University of Canterbury and one of the inventors of a transduction water heater, responded.
The word induction in this sense refers to inducing an electric current in metal using a changing magnetic field, rather than having a contact method like the resistive elements in a hob.
With induction heating, heat is produced directly in the pot rather than being conducted from a hot element. This way, only the pot, and hence the water and food, is heated. The element stays relatively cool.
The idea works on pots made of steel, copper or aluminium. Just how well depends on their shape and size. You would need to experiment with this. The magnetic field is generated by designing a copper coil in the space of the hob where a normal resistance element is placed. The coil is put in a horizontal position so that the magnetic field goes up through the pot and then out the sides and around the coil and back up again.
We use alternating current, as the currents induced in the pots only occur if the magnetic field is changing. We can use mains frequency, 50Hz, or a higher frequency, but that needs a changer which adds to the cost and complexity.