You might remember the heroic role that newly-invented radar .
But even in its earliest years, as it was helping win the .
war, radar proved to be more than an expert enemy locator. Radar .
technicians, doodling away in their idle moments, found that they .
could focus a radar beam on a marshmallow and toast it. They also .
popped popcorn with it. .
.
Such was the beginning of microwave cooking. The very same .
energy that warned the British of the German Luftwaffe invasion .
and that policemen employ to pinch speeding motorists, is what .
many of us now have in our kitchens. It's the same as what .
carries long distance phone calls and cablevision. .
.
Hitler's army had its own version of radar, using radio .
waves. But the trouble with radio waves is that their long .
wavelength requires a large, cumbersome antenna to focus them .
into a narrow radar beam. The British showed that microwaves, .
with their short wavelength, could be focussed ina narrow beam .
with an antenna many times smaller. This enabled them to make .
more effective use of radar since an antenna could be carried on .
aircraft, ships and mobile ground stations. .
.
This characteristic of microwaves, the efficiency with which .
they are concentrated in a narrow beam, is one reason why they .
can be used in cooking. You can produce a high-powered microwave .
beam in a small oven, but you can't do the same with radio waves, .
which are simply too long. .
.
Microwaves and their Use .
.
The idea of cooking with radiation may seem like a fairly new .
one, but in fact it reaches back thousands of years. Ever since .
mastering fire, man has cooked with infrared radiation, a close .
kin of the microwave. .
.
Infrared rays are what give you that warm glow when you put .
your hand near a room radiator or a hotplate or a campfire. .
Infrared rays, flowing from the sun and striking the atmosphere, .
make the Earth warm and habitable. In a conventional gas or .
electric oven, infrared waves pour off the hot elements or .
