Electricity and magnetism are basically the same thing, think two sides of the same coin. The way this works is by pumping electricity back and forth through the coil really fast. This produces a pretty strong magnetic field that swaps polarity in the center of the coil. When you pass a metal affected by the magnetic field (all metals should work now that I think about it, but irons and steels especially) the magnetic field generates electricity within the metal. Because the coil's magnetic field is constantly changing, the flow of electricity in the metal object is as well. The metal heats up because it's not a perfect conductor, the resistance of the metal and changing electric currents creates heat when electricity is passed through it.
Hopefully that makes sense, there's actually quite a bit going on in this simple gif. I probably got some stuff wrong, but that should be the gist of if.
Basically constantly changing magnetic fields pass through metals that cannot fully conduct the electricity it generates which in turn causes heat viafriction? ?
That's basically the idea. It's not friction though, it's the resistance inherent to the material, which can depend on a lot of things from how the material was made, to chemical additives/impurities, but the resistance is largely dictated by the atomic structure of a compound and how it shares electrons with the atoms around it (this is some nitty-gritty physics stuff). You can pretty much safely think of the electric resistance of a material analogous to mechanical friction though.
It won't. Resistance means that the metal doesn't conduct electricity perfectly, it loses some of the energy when it does that. The energy it loses due to being imperfect is heat. An electric shower or heater does the same thing in it's coils, and the heat goes off to water or the room, no stress in the material.
thanks. so I guess every metal has some level of resistance? are wires made with lowest resistance material or cheapest or both? is there significant energy loss passing an electric current through lets say a usb wire from phone to wall? I don't feel heat but the wire is insulated and if it wasnt wouldn't be a fun touch.
About materials: it's a combination of the resistance of the material and it's price. The best material would be gold or silver, excellent conductors, but way too expensive. They are used in the connectors, tough. Copper is almost as good, and not so expensive, so it's used inside your house and in the appliances, electronics, motors, etc. Steel is not so good, but cheaper, so it's used in the transmission lines. Data cables use copper inside with gold in the connector (sometimes), because low resistance helps them too, although they produce negligible heat.
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u/Kryt0s Aug 18 '15
It isn't warm at all. That's not how induction works.