Glass turntable
Metal floor
The glass turntable of your microwave
oven lets microwaves pass through. Then
they bounce off a metal floor, back through
the glass turntable, and are absorbed by the
food.
Microwaves may not reach the center of a
roast. The heat spreads to the center from
the outer, cooked areas just as in conven-
tional cooking. This is one of the reasons for
letting some foods (for example, roasts or
baked potatoes) stand for a while after
cooking, or for stirring some foods during
the cooking time.
The microwaves disturb water molecules
in the food. As the molecules bounce
around bumping into each other, heat is
made, like rubbing your hands together.
This is the heat that does the cooking.
Microwaves pass through most glass,
paper and plastics without heating them
so food absorbs the energy. Microwaves
bounce off metal pans so food does not
absorb the energy.
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