When microwaving food, why does one area of a round ceramic plate get hot while the other stays cold?

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For example, I’ll microwave food centered on the plate for 3 minutes on the spinning tray. When I go to take it out, the right side might be cool to the touch, while the left side is nuclear-hot.

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Anonymous 0 Comments

Microwaves create standing waves of electromagnetic radiation. Where those waves end up is super difficult to predict, even for supercomputers. Where those waves are at their peak they will heat the fastest. To make things heat evenly manufacturers started including the spinning tray, so that no part of your food will be stuck in a peak while another sits in a cold spot for very long.

But yeah they’re super unpredictable and it’s probably the case that one part of the plate spent more time in a hot spot than the other.

Also, food (more specifically, the water in it) absorbs microwaves much better than ceramic so parts covered in food will heat up faster by conducting heat from the hot food faster than bare parts will heat from the microwaves alone.

Anonymous 0 Comments

[There’s a what-if xkcd](https://what-if.xkcd.com/131/) that covers this pretty well, but basically because the microwave is sending, well, waves of radiation to agitate water molecules in the air, food, and everything around it to create heat; if you visualize a sine wave and look at the mid point of a waveform between a peak and a valley, where the “0” line on the graph would be: where the microwaves pass through there is going to be a cold spot where things don’t heat as effectively as when the things go through a hot spot. The rotating platter is a way to get this to change.

This is also why, for instance, you can microwave a hot pocket and take one bite that is still frozen and then the next will be lava, and *also* also why it’s recommended, generally, to cook things on a lower setting for a longer time, and to let microwaved things sit a minute or two before serving/eating: giving things time to sit isn’t necessarily to cool them off, but to allow the system to reach equilibrium in some heated state, where the heat from the hot spots spreads out into the cold spots.