2. Microwave interactions – matter

2.1 Materials heated by microwaves

Experience with household microwave ovens shows that food generally heats up very quickly when exposed to microwaves. The materials of the containers holding the food also heat up more or less quickly, depending on their nature. The metal walls of the oven, on the other hand, remain cool.

In fact, only certain insulating materials or poor conductors of electricity are able to heat up under the action of microwaves. At the molecular level, these materials appear as electrically neutral entities, but with a dissymmetrical distribution of their partial ionic charges. In other words, one part of the molecule is positively charged, the other negatively. These molecules thus form electric dipoles.

In the absence...