Eli5 : Why are sparks created when microwaving metal?
In: 5
Dielectric heating (microwaving) is when the polarity of a molecule aligns itself in an electromagnetic field and as that undergoes changes like with a microwave oven the molecule rapidly moves heating up in the process. However metal doesn’t absorb the microwaves instead they bounce off the metal and bounce around the inside with nowhere to go until the energy discharges like a thunderstorm inside the microwave. https://youtu.be/V0dtq3rCEjw
Metal, like a spoon, doesn’t always create sparks in a microwave though. And sometimes it can actually be safer to put a spoon in a glass of water when you heat it. Because the spoon can reduce the risk of the water getting superheated (above boiling temperature without actually boiling).
https://physics.stackexchange.com/questions/234042/should-i-place-a-spoon-in-a-cup-of-liquid-before-heating-it-in-a-mircowave
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