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Q & A: How a Microwave Heats Food

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Most recent answer: 06/01/2015

What this website says is false. Microwave ovens actually heat your food by shooting electromagnetic waves at it. These waves have a frequency in the microwave range such that water molecules will absorb them and start vibrating. Molecular vibrations are what we sense as temperature, so the longer you microwave the food, the hotter it will get. However, the electromagnetic waves can only penetrate a certain depth into the food. This depth is dependent upon the frequency of the microwaves, and various electromagnetic properties of the food, particularly the water content.


(published on 04/01/2012)

Follow-Up #1: microwave heating ceramics

So then why does the dish sometimes get far hotter than the food? A ceramic plate or mug, presumably, doesn't contain any water molecules.
- Heather (age 36)
Bay Saint Louis

That's a very good point. Many materials, not just water, absorb the microwaves used in these ovens. Most ceramics intended for kitchen use now don't absorb them very much, but some do. We have one or two cups that seriously overheat in the microwave.

Mike W.

(published on 06/01/2015)

Follow-up on this answer.