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A microwave oven heats food by exposing it to electromagnetic radiation at a frequency of 2.45 GHz. At this frequency, the oscillating electric field of the microwave causes polar molecules — most importantly water — to rotate back and forth rapidly in an attempt to align with the changing field. This molecular rotation generates friction and heat. The process is called dielectric heating. The key point is that microwaves penetrate food to a depth of several centimetres, heating it from the inside as well as the outside, which is why cooking is much faster than in a conventional oven where heat must conduct inward from the surface. Contrary to a popular misconception, microwave ovens do not specifically target water molecules by matching their resonant frequency; rather, 2.45 GHz was chosen for practical engineering reasons (penetration depth, hardware cost) and happens to be effective at agitating water molecules.
answered by Omniscientia Team · 157 words · 18 Mar 2026