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An induction hob works like an electrical transformer it transfers electrical energy into the pan, using a time-varying magnetic field. A coil of wire is mounted underneath the cooking surface of the induction hob, and a large alternating current is made to flow through that wire. This current creates a changing magnetic field. When an electrically conductive pan is brought close to the induction hob cooking surface, this magnetic field induces an electrical current in the pan.
The metal pan is not a perfect conductor, and as a result the eddy currents created in the pan by the induction hob encounter some electrical resistance. This resistance converts the current into heat. The result is that the metal pan, and only the metal pan, heats up. Heat is transferred from the pan to the food inside the pan by conduction. The cooking surface of the induction hob is designed to be a good thermal insulator, so that a minimum of heat is transferred from the pan to the cooking surface of the induction hob (and thus wasted). In normal operation, the induction hob cooking surface stays cool enough to touch without injury.
If the pan is made from a magnetic or electrical insulator, then no current can flow through the pan. This means that no heat will be generated. Inductive hobs do not work with pyrex, glass or ceramic.
When the Induction Hob is in operation current is flowing through both the pan and the driving coil; but the pan should heat up, and the coil should stay cool, since any energy that does not go in to heating the pan is wasted. This occurs because the Induction hob coil and the pan are made of different metals. The induction hob coil is typically made from copper or another metal with high electrical conductivityThe pan is typically made from stainless steel or iron which is much less conductive. This means that most of the energy will become heat in the high-resistance steel, and the induction hob driving coil will stay cool. (The partition of heat is not completely determined by the materials' electrical conductivities. The effective resistance that the eddy current sees is affected by the ferromagnetic steel's permeability which determines the skin depth. The geometry of the pan and the induction hob driving coil are also important.)
With aluminum or copper cookware, this is not the case; the current will heat the induction hob driving coil just as much as it will the pan. The induction hob will therefore not work efficiently.
With iron or steel cookware, some heat is also generated due to the ferromagnetic material's magnetic hysterisis. This is a smaller component (typically less than 7%) of the total heat generated. These two contributions, I2R losses from eddy currents and hysteresis losses, or "copper losses" and "iron losses", are similar to the two identically-named loss mechanisms in an electrical transformer. In a transformer, these losses are undesired, because the useful output is electrical power; in an induction hob the useful output is heat, so these "losses" are what is desired.
Induction Hob - FREE COMMERCIAL INDUCTION HOB TRIAL FOR COMMERCIAL USERS
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