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The Physics Experience |

The Physics Experience

MADISON, Wis. (WMTV)– How can you have heat without fire? It’s not magic, it’s science. Specifically, the science of induction, where strong electric fields can create heat. Induction cook tops use this to heat food without any flames or direct heat, cooking more efficiently than their gas or conventional electric cousins. And this lack of direct heat makes them safer, too: you can even put paper between an induction cook top and a pan, and it won’t catch light.


They create heat in the base of the cookware.s quicker. They are also easier to clean, because the flat glass or ceramic surface has no gaps or grills to collect spilled food, and the food doesn’t get burned onto the surface. If you spill something, one quick swipe with a damp cloth will clean it up. They are also quicker to control and more precise, again because the heat is generated inside the cookware, and so react quicker when you turn the dial up or down.

So why aren’t they more common? It’s partly a comfort thing; most US consumers don’t like them because they grew up on gas rings. Samsung has recently introduced an interesting solution to this problem: a cook top that projects an LED flame that shows the ring is on , and indicates the heating level. Induction cook tops are also more expensive, because they are more complex than the more common gas type.

But the main issue is with which cookware you can use with them. Because of the way they work, many types of pans just don’t heat up with induction cook tops. If you have copper bottom, glass or aluminum pans, they don’t get hot when you put them on an induction cook top.

How they work:
Induction cook tops use one of the odd quirks of electromagnetism: if you put certain materials into a rapidly alternating magnetic field, the material absorbs the energy and heats up. That’s because the field creates electrical currents inside the material, and the resistance of the material converts this electrical energy into heat, which is transferred to the food inside the pan.

Right underneath the cooking area of an induction cooktop is a tight spiral of cables, usually made of copper. The cooktop controller pushes an alternating current through this coil, which changes direction usually 20 to 30 times a second. This current flow creates a magnetic field above the coil. As the current alternates back and forth, the magnetic field does the same. If you put a pan on the surface (so it is just above the coil), this magnetic field induces (hence the name) an electrical current in the metal base of the pan. As the magnetic field alternates, this current flows back and forth (which is why it is often called an eddy current, as it swirls around like an eddy in a river). The metal resists this flow, and, like an electric heater, creates heat, which is conducted into the food through the metal of the pan. If you want to gently heat the food, the cook top pumps a lower current through the coil, so the cookware generates less heat, and the food warms slower.

Category: Cookware Pans  Tags: ,  Comments off
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