Microwave Radiation

Microwave radiation, when absorbed by matter, causes molecules to tumble at a greater rate. This increased rotational energy causes the molecules to heat up. When the frequency of microwaves is chosen to correspond with the rotational motion of water, the water heats up. This is the basis for cooking with microwave ovens. Water in the food absorbs microwave radiation, its rotational motion and thereby its temperature increases, and in turn this causes the food to cook.

Radar, used by aircraft and police for example, falls within the microwave region of the electromagnetic spectrum. The story has been told that in the early days of radar, when large powerful radar arrays were placed in northern Canada and Alaska to warn of early missile attacks by the Soviet Union, military personnel would stand in front of the radar transmitters to keep warm. In fact, they were unknowingly cooking themselves.

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