Microwaves are used in a microwave oven because their frequency
- A. is absorbed strongly by water molecules, which then rotate and heat the food
- B. ionises the food
- C. reflects off water
- D. changes the chemical composition of the food
Explanation
The oscillating field makes polar water molecules flip back and forth, and the friction between them heats the food from within rather than only at the surface. Microwaves are non ionising, since their photon energy is far too low to remove electrons, so they do not make food radioactive. Metal containers are unsuitable because they reflect the waves and can cause arcing.
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