How does microwave radiation heat food inside a microwave oven?
AIt makes the metal walls of the oven vibrate
BIt makes polar molecules such as water rotate faster
CIt ionizes the food, releasing stored nuclear energy
DIt reflects visible light back and forth inside the food
Answer & Solution
Correct answer: B. It makes polar molecules such as water rotate faster
1. Microwaves used in kitchen ovens have the right amount of energy to make polar molecules, such as water, rotate faster.
2. This rotational energy is given up to surrounding matter as heat, which is what warms the food.
3. No ionization or nuclear process is involved, so the food is heated rather than made radioactive.
4. Visible light plays no part in this mechanism, since the oven uses microwave frequencies, not light frequencies.
_Source: OpenStax Physics (CC BY 4.0), Ch 15 "Light", section 15.1 The Electromagnetic Spectrum_
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