burners and are converted to heat when they strike .
air inside and the food. .
.
Microwaves and infrared rays are related in that both are .
forms of electromagnetic energy. Both consist of electric and .
magnetic fields that rise and fall like waves on an ocean. .
Silently, invisibly and at the speed of light, they travel .
through space and matter. .
.
There are many forms of electromagnetic energy (see .
diagram). Ordinary light from the sun is one, and the only one .
you can actually see. X-rays are another. Each kind, moving at .
a separate wavelength, has a unique effect on any matter it .
touches. When you lie out in the summer sun, for example, it's .
the infrared rays that bring warmth, but ultraviolet radiation .
that tans your skin. If the Earth's protective atmosphere weren't .
there, intense cosmic radiation from space would kill you. .
.
So why do microwaves cook faster than infrared rays? .
.
Well, suppose you're roasting a chicken in a radar range. .
What happens is that when you switch on the microwaves, they're .
absorbed only by water molecules in the chicken. Water is what .
chemists call a polar molecule. It has a slightly positive charge .
at one end and a slightly negative charge at the opposite end. .
This peculiar orientation provides a sort of handle for the .
microwaves to grab onto. The microwaves agitate the water .
molecules billions of times a second, and this rapid movement .
generates heat and cooks the food. .
.
Since microwaves agitate only water molecules, they pass .
through all other molecules and penetrate deep into the chicken. .
They reach right inside the food. Ordinary ovens, by contrast, .
fail to have the same penetrating power because their infrared .
waves agitate all molecules. Most of the infarred radiation is .
spent heating the air inside the oven, and any remaining rays are .
absorbed by the outer layer of the chicken. Food cooks in an .
ordinary oven as the heat from the air and the outer layer of the .
