A look at the origin of microwave ovens. Many kitchens now have a microwave oven fitted, and they have reduced cooking times dramatically.

What are microwaves?
In frequency (rate of vibration) and wavelength, microwaves fall in the electromagnetic spectrum between infrared rays and radio waves.

Microwaves are nonionizing energy. They are much less powerful in effect and do not have sufficient energy to dislodge electrons from atoms, which is why man has felt relatively free to utilize this form of energy for its beneficial advantages.

To ensure certain safety standards, the Food and Drug Administration (FDA) has the responsibility for carrying out an electronic product radiation control program mandated by the Electronic Product Radiation Control provisions of the Food Drug and Cosmetic Act.


What They Are Used For
About 80 years ago there were no man-generated microwaves. Only small amounts of microwave radiation from the sun and other sources in earth's galaxy found their way into our atmosphere. But then, prior to World War II, radar was developed. Thus microwaves first came to public notice, since radar uses microwaves.

The medical world has its own uses for microwaves: for sterilization, for experimental use in cancer treatment, to retard tumor growth, and in diathermy machines, which heat body tissues for treatment of such ailments as bursitis, arthritis, and muscle aches and sprains.

                    

How Do Microwaves Ovens Work?
The reason the energy can be used in microwave ovens to cook food is simple: though metals reflect microwaves, foods absorb them. So a metal box, the oven, reflects the beams of microwaves, which bounce around inside the oven until they hit the food. Microwave heating works by heating the water in foods. The frequency used in microwave ovens optimally heats water molecules, vibrating at an incredible two and a half billion times a second. This friction results in heat, and this heat does the cooking. In effect, the food produces its own heat.

In a microwave oven very little of the energy goes to waste heating the oven or the air within it, as happens in conventional cooking. Also, very little goes to waste heating the cooking containers because in microwave cooking you use glass, paper, or plastic, all of which simply allow microwaves to pass through them, neither absorbing nor reflecting them. So when a small amount of food receives the full brunt of the microwaves' power, it cooks very quickly.

                                                   

For example, in a conventional oven, a baked potato might require from 45 to 60 minutes to cook. In a microwave oven, one potato might be cooked in approximately 2 1/2 to 9 minutes, depending on the size of the potato and the make and model of the oven. If two potatoes are cooked, it may increase the cooking time to 5 to 15 minutes. The increase in cooking time is due to the microwave energy being divided two ways instead of the full amount being absorbed by one potato. This vast speedup of cooking times when using microwave ovens represents their principal appeal.

                     

One of the problems with conventional microwave ovens is that food never got browned. A convection microwave is a combination of a standard microwave and a convection oven. It allows food to be cooked quickly, yet come out browned or crisped, as it would from a normal convection oven. Convection microwaves cost more than a conventional microwave and are really only considered cost-effective if primarily used just to heat more than just drinks or frozen food. They are usually used for cooking prepared dishes.

Today there are many millions of these ovens in use around the world.
Microwave ovens were first marketed to the general public in the U.S. in 1967, with only 10,000 ovens sold that first year. But sales have skyrocketed phenomenally since then. By 1986, roughly 25% of households in the U.S. owned a microwave, up from only about 1% in 1971. Current estimates hold that over 90% of American households have a microwave.








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