How does a microwave heat food?

"Microwave ovens cook food by generating intermolecular friction between the molecules of the food. The microwaves cause water molecules to vibrate; the increased friction between the molecules results in heat. Microwaves could affect your tissue in a similar way if they were able to escape from the microwave oven. read more

Heat is created by the resulting friction of the water molecules reversing direction millions of times a second. Conventional ovens rely on conduction to slowly spread the heat from the outside of the food to the inside; by the time the inside is cooked, the outside may be over-cooked. read more

Microwaves heat water by jerking the water molecules around, so to speak. Each water molecule has a slight positive electric charge on one side and a slight negative charge on the other. As microwaves pass by, they exert forces on those charges, first one way, then the other, several billion times per second. read more