Is Induction Cooking Ready to Go Mainstream?
Explaining how it works is also a challenge. Ms. Simpson tried with her grandfather, telling him that an electrical current produces a magnetic field that excites iron molecules and heats the pan and its contents.
“He looked at it like it was devil voodoo magic and walked way,” she said.
The article mentions that the only cookware suitable for induction cooking are steel or cast iron, i.e. ferromagnetic materials. I was, however, under the impression that induction works with all pots & pans made of conductive material -including of course copper or aluminum- as it relies on eddy current generation. Any insights on the issue?
Re: Markos
I was wondering the same thing.
Obviously eddy current generation works with any conductor. But I’d expect for eddy current heating, you want the timescale of resistive heating to be matched to the frequency that you’re inducing eddy currents. Generally I think the stovetops work with magnetic fields oscillating at ~30 kHz. I think in a typical aluminum or copper pan the conductivity is sufficiently high that the I^2 R losses don’t “pull out” a large fraction of the eddy-current energy in a single oscillation. If your circuit is smart this won’t be “lost energy”, since it’ll look like a highly reactive load, but it does mean that the transfer of energy to the pot will be slower (assuming there’s some limits to the currents in your stovetop inductive coils).
What also helps with the ferromagnetic pans are the “concentration” of field lines inside the pan (as happens with any ferromagnetic material) and the low skin depth increasing the effective electrical resistance.
Re: Anon. Coward
I couldn’t hope for a better explanation… Thanks a lot!
In addition to what A.C. has said, there is also the hysteresis of ferromagnetic materials ; it’s not purely I^2R losses from eddy currents, but also mechanical effects from moving the domains around, though this is a relatively small effect — the big winner is the high magnetic permeability of iron.