1 x 10 ** - 4 m to 1 x 10 ** 2 m
James Clerk Maxwell in 1864.
Microwaves were first used for radar in WWII.
(1939-1945) The development of microwaves is only one step of the gradual
evolution of the concept and application of electromagnetic waves. Maxwell
formulated a set of equations supporting all electromagnetic phenomena, which
became known as Maxwell's equations. Hertz's experiment proved further
generalizations and applications which led to the development of the microwave.
In a microwave oven, a magnetron generates and
shoots out a beam of microwaves. The beam strikes the metal blades of a stirrer
fan, which reflects and scatters the microwaves throughout the oven. The
microwaves bounce off the metal waves and travel through plastic, glass, or
paper to heat up water molecules in the food.
Microwaves are used in:
In some cases microwaves relieve symptoms
better than drugs. The use of microwaves is safer than surgery. For example,
the wave can heat enlarged prostates, therefore killing extra tissue.
Microwaves can decrease air pollutants,
disinfect hospital waste, improve dry cleaning solvents, and clean up
Satellite communications have used microwaves
in the past. Scientists use microwaves to make chalcopyrite, a semi-conductor,
made of copper. Microwaves can also be used to remove materials, and chemicals
that can be used for analysis.
Microwave ovens are used to heat and re-heat food evenly by agitating water
molecules in food. Some burglar alarms send continuous microwaves (short radio
waves) into an area. Any movement in that area disturbs the wave pattern and
sets off the alarm.
Microwaves are used in cellular phones,
telephones, telegraphs, television, and satellites.
Microwaves leaking from an oven may pose a hazard to people nearby. They
are dangerous for women who are pregnant, because of the unknown defects caused
by radiation leakage.
Metal containers should be avoided because
they reflect microwaves, and prevent the microwaves from entering the food.
Securing door seals and proper door closure helps to prevent microwave leakage.
Microwave ovens that don't close securely should never be used.
Celestial bodies that Emit
Microwaves are not known to be
produced by any celestial bodies.
Interesting Information not Included Above:
Microwaves move at the speed of light, which is 186,000 miles per second
(300,000 kilometers per second) through empty space.
Microwaves are a type of electromagnetic energy like light waves. The one
difference is that microwaves cannot be seen by the human eye. Microwaves have
longer wavelengths than light waves. Like light waves, microwaves may be
reflected and concentrated. Microwaves pass easily through rain, smoke, and fog
which block lightwaves. Microwaves can pass through the ionosphere (which
surrounds the earth and blocks or reflects longer radio waves).Microwaves are
used in aircraft. High altitude power microwaves can be developed and used for
communication and laser beam direction.
In the future, microwaves will be able to be used in landing systems for
airplanes, and for the use of global navigation satellites.
Recent magazine article on microwaves:
Scientists are searching for better ways to break down hazardous wastes.
Improved microwave heating methods can break down air pollutants and clean up
contaminated soil. By removing water from radioactive sludge, it means less
handling of hazardous waste and saves time and energy. Old electric circuits
have become a mounting source of hazardous waste. With microwaves, researchers
can recover precious metals and melt remainders. Microwaves can cook
contaminated earth that is soaked with dangerous pentachlorophenols, destroying
99.9 percent of the noxious chemicals.
"Microwave heating" April