The Misconception

• The idea that microwaves cook from the middle out is a nothing but a fallacy. In fact, microwaves can only penetrate to a 1-inch depth, so if your food is any thicker, the center may still be cold after cooking. This is why some recipes make it a point to mention rotating or removing the food every few minutes to stir. Microwaves do cook the outer edges of food, but it is another transfer of energy -- heat transfer by conduction -- that cooks the inside.

The Magnetron

• Magnetron is a big name for a small electron tube that produces microwaves inside a microwave oven. When you plug a microwave oven into a wall socket, electric energy puts the magnetron to work converting the electrical energy to microwave energy. These microwaves bounce back and forth along the inside walls of the microwave until they come in contact with the food that is on the glass carousel. Once this happens, a force called friction eventually starts the cooking process.

Good Vibrations

• Molecules inside food, namely water molecules, absorb microwaves. When the microwaves make contact with the food, these water molecules begin to vibrate at a high frequency. The high speeds of the vibrating water molecules cause them to rub against each other, resulting in friction. This friction creates heat, which ultimately cooks the food inside the microwave oven. It is important to note that the higher the water content of the food, the faster it cooks. As the outer edges of the food heat up, the heat spreads to the middle.

Conventional Comparison

• Unlike a conventional oven, the inside of the microwave does not heat up. This is because all of the microwave energy is directed towards the food. Because all of the microwave energy’s attention focuses on the food, the food conveniently cooks faster and more uniformly than in the conventional oven. Because microwaves work with the water content already present in the food, additional water is unnecessary during the microwaving process. Without the additional water, foods are able to retain their vitamin and mineral content, unlike foods cooked in a conventional oven or on the stove.