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Microwave energy has been used in this country to cook and reheat food
since early experiments with RADAR in World War II. Microwaves are
present in the atmosphere all the time, both naturally and from manmade
sources.
Manmade sources include radar, radio, television, telecommunication links
and mobile phones.
Microwaving Principles
In a microwave oven, electricity is converted
into microwaves by the MAGNETRON.
REFLECTION
The microwaves bounce off the metal walls
and the metal door screen.
TRANSMISSION
Then they pass through the cooking
containers to be absorbed by the water
molecules in the food, all foods contain
water to a more or lesser extent.
HOW MICROWAVES COOK FOOD
Microwave Water Molecule Absorption Vibration
The microwaves cause the water molecules to vibrate which causes FRICTION, i.e.
HEAT. This heat then cooks the food. Microwaves are also attracted to fat and sugar
particles, and foods high in these will cook more quickly. Microwaves can only
penetrate to a depth of 1
1
⁄
2
-2 inches (4-5 cm) and as heat spreads through the food by
conduction, just as in a traditional oven, the food cooks from the outside inwards.
Oven cavity
Magnetron
Waveguide
