十万个为什么·科学启蒙30篇（4）

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为什么微波炉加热食物不均匀

Microwaves heat food by making water molecules vibrate rapidly and generate heat.
But these waves form standing patterns inside the oven, creating hot and cold spots.
The center of a turntable rotates food to pass through different wave intensities.
Dense or thick foods—like a potato—absorb energy unevenly because microwaves penetrate only 1–2 cm deep.
Cold zones often occur where wave peaks cancel out, especially in corners or large flat areas.
Metal reflects microwaves, so foil or containers with metallic trim cause dangerous arcing and shielding.
Stirring soup or letting food rest after heating helps distribute heat more evenly via conduction.
Unlike ovens that warm air gradually, microwaves target molecules directly—so timing matters more than temperature.