How Microwaves Work (part 2)

(continued from How Microwaves Work part 1)

In microwave cooking, the radio waves penetrate the food and excite water and fat molecules evenly throughout the food and all the molecules are all excited together. However, radio waves penetrate unevenly in thick pieces of food, therefore they don’t make it all the way to the middle. There are also “hot spots” caused by wave interference, but you get the idea. The whole heating process is different because you are “exciting atoms” rather than “conducting heat.”

In a microwave oven, the air in the oven is at room temperature, so there is no way to form a crust. That is why microwavable pastries sometimes come with a little sleeve made out of foil and cardboard. The sleeve reacts to microwave energy by becoming very hot. This exterior heat lets the crust become crispy as it would in a conventional oven.

The cooking chamber itself is a Faraday cage enclosure which prevents the microwaves from escaping into the environment. The oven door is usually a glass panel for easy viewing, but has a layer of conductive mesh to maintain the shielding. Because the size of the perforations in the mesh is much less than the wavelength of 12 cm, most of the microwave radiation cannot pass through the door.

(more to come about Microwaves and your food…)