Get your own Free Home Page
Most conventional cooking is accomplished by placing food in a hot environment. In an oven, on a stovetop, under a boiler, or on a grill, heat is conducted from the external source to the surface of the food and it slowly penetrates to the food's interior.
In a conventional oven, the air surrounding the food must be heated first before it can cook the food. Then the outer layer of food heats and cooks before the heat gradually penetrates to the center of the food by conduction.
Microwave ovens contain a magnetron tube, which converts electricity into microwaves rather than heat. Microwaves are high-frequency electromagnetic waves similar to radio waves. Early in the history of microwave ovens it was pointed out that microwave ovens cooked by radiation. At that time people thought of "radiation" as the energy that is realeased by an atom or nuclear bomb. Thus people sometimes that they had something like a bomb in their oven, that they were nuking their food and someday they might start glowing in the dark. They also thought that microwave radiation like atomic radiation stayed around in their oven and in their food. Since microwaves are similar to radio waves, there is no residual radiation. The microwaves are converted to heat when they contact food.
In a microwave oven, no preheating of the cooker cavity is needed. The microwave energy actually penetrates the food, passing straight through the surrounding air, thus saving cooking time and electricity. The microwaves themselves are not hot, but are attracted and absorbed by water, fat and sugar in the food. The microwaves cause the water, sugar or fat molecules in the food to rotate rapidly (at the rate of 5 billion times per second). They bump into each other, causing friction, and it is this heat which actually cooks the food. A similar action happens when you rub your hands together-feel how warm they get.
Microwaves penetrate food to a depth of about 1 1/2 in. In large items of food, or large quantities, the heat is spread by conduction just as it is in conventional cooking.
The power level you select determines the speed of cooking. Many foods cook successfully on 100'S,(full power). However, personal tastes vary and if the cooking result is not to your liking, next time you cook that food try using a lower power level and adjusting the cooking time. The slightly longer cooking time is worth it in order to get the best results. Other foods, such as casseroles, benefit from longer slower cooking so they are cooked at a lower power level. In this way it is similar to adjusting the temperature in a conventional oven.
Microwaves cannot penetrate metal so are totally contained within the cooker cavity. The holes in the door panel allow you to see inside the oven during cooking, but they are not large enough to allow the microwaves to pass through. Although microwaves do not directly heat cookware, heat building up in food can be transferred to its dish. So containers can become very hot. Always use potholders when removing dishes from the microwave.
Return to: Other Stuff You Should Know
Return to: Mr. Microwave