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Concept

Dielectric heating

A microwave oven with an illuminated interior shows the dielectric heating process, where an oscillating electromagnetic field causes polar molecules in food to rotate rapidly, generating heat through friction.

The mechanism by which a microwave oven cooks food. An oscillating electromagnetic field forces polar molecules — mainly water — to rotate back and forth billions of times a second. Friction between the rotating molecules dissipates the field's energy as heat. Substances with no polar molecules, such as dry ceramic or glass, are almost transparent to the field and barely warm at all.

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