Interesting Facts About Microwaves

Microwaves

• Microwaves are a form of electromagnetic radiation. Metal reflects these rays, but they pass through glass, plastic, china and paper with no effect, and food absorbs them. This makes them a suitable energy source for cooking food.

How Microwave Ovens Work

• The microwaves generated in the oven make water molecules vibrate. This motion leads to friction, which in turn leads to heat, which cooks the food. Even dry foods, such as crackers, have water in them. Microwave ovens don't heat frozen foods well, as food needs liquid water for the heating to occur.

Safety

• The U.S. Food and Drug Administration enforces standards for microwave ovens for the maximum radiation they can produce. The standard of 5 milliwatts of microwave radiation per square centimeter is far below the minimum level known to cause harm to people. Microwaves also have a safety system that stops the production of microwaves when someone opens the oven door.

The Defrost Setting

• The microwave oven's defrost setting works in a different way than regular cooking. When defrosting, the oven heats the frozen food briefly and then waits for a while before repeating the process. The waiting period allows the heat to be distributed throughout the food. Repeating this process ensures that the food defrosts evenly.

Hot and Cold Spots

• Microwave ovens may develop hot and cold spots in which the food cooks quickly or not at all. As the microwaves bounce around the inside of the oven, they sometimes cross each other's paths. In some places within the oven, the interference is such that the waves cancel each other out, producing the cold spots; in other places, the microwaves reinforce each other, creating hot spots. The turntables in microwave ovens rotate the food so that it passes through hot and cold spots and cooks more evenly.

Exploding Food

• Cooking eggs in the microwave causes them to explode. As the inside of the egg heats up, it expands. However, the shell is a solid rather than a liquid and doesn't heat and expand as rapidly. The pressure from the developing steam inside causes the shell to crack and the egg's insides to explode through the crack. Not all exploding food is messy. Microwave popcorn "pops" for the same reason.