In Case of Hunger, Induce Cooking

In the apartment here in France, we have a kitchen appliance I've never used before: an induction stove. Growing up, I used the two other kinds of electric stove: resistive hotplates, and halogen lamps. In the first case, current is run through a metal coil, which heats up due to resistance – The electrons bump into the atoms in the coil, transferring energy. Halogen lamps put out infrared light, which is absorbed by whatever is on the stove. Induction cooking takes an entirely different tactic though.

Underneath the glass surface, each element has a coil of wire, similar to the resistive hotplates, but with a different purpose:

By Wdwd - Own work, CC BY-SA 3.0, Link

The resistive hotplates use a coil to spread the energy evenly over the bottom of a pot, but induction cooktops take advantage of Faraday's law:

This says that when an electric field (like the one in a wire carrying current) goes in a circle, it produces a changing magnetic field perpendicular to the surface. Since we use alternating current, the electric field in the stove looks like this:

The left side of the equation quantifies the circular motion you see above. The right side tells us that this motion produces a changing magnetic field coming out of the screen in the plot above.

That magnetic field enters the pot sitting on the stove, and now the relationship is flipped: The changing magnetic field produces an electric field. The pot is a conductor, meaning it has free electrons, which respond to the electric field by accelerating. Just like the resistive hotplate, we now have electrons moving through metal, which results in heat, but this time, it's happening in the pot itself.

By inducing current directly in the pot, we get much finer control over the heat applied – I've been amazed by how quickly things heat and cool on this stove. It's also more efficient than other stoves – Resistive hotplates often have a solid disk enclosing the element to help spread the heat evenly, but this requires more energy to heat up, and that energy is usually wasted after cooking.

The one downside to this method is that the pot needs to be able to absorb that magnetic field efficiently. That means it needs to be ferromagnetic (iron or stainless steel), and it needs to be a certain thickness. Without thinking about that latter requirement, I bought a super-cheap flimsy frying pan, and the stove refused to heat it; the heating cycle only turns on if it senses a compatible pan.

I generally find gas stoves terrifying, since they put out tons of heat, plus explosive/noxious fumes. This induction stove seems like the best of both worlds: fast heating, and low risk!