a m­icrowave oven uses microwaves to heat food. Microwaves are a type of wave that are sandwiched between radio waves and infrared radiation on the electromagnetic spectrum. In the case of microwave ovens, the commonly used wave frequency is roughly 2,450 megahertz (2.45 gigahertz).

Waves in this frequency range have an interesting property: They're absorbed by water, fats and sugars. Once absorbed, they're converted directly into atomic motion -- heat. These waves boast another interesting, related property, too: They're not absorbed by most plastics, glass or ceramics. Metal reflects microwaves, which is why metal pans don't work well in a microwave oven. It's also why the devices have metal walls -- for reflection.
Microwaves used for cooking, on the other hand, are electromagnetic waves possessing frequencies around the 2.45 GHz range. Now, electromagnetic waves are waves made up of alternating electric and magnetic fields. For this discussion, we’re more concerned with the alternating electric fields because charged particles readily react when exposed to them. That is, when a positively charged particle is exposed to an electric field, it experiences a force (due to the field) pointing in the direction of the field. By contrast, when a negatively charged particle is exposed to the same field, it experiences a force in the direction opposite to the field.

Now, since an electromagnetic wave (like the microwave) is made up of alternating electric fields, a