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Thermal
Radiation - Heat Transfer
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[ Heat
Transfer Table of Contents]
Radiant heat transfer involves the transfer
of heat by electromagnetic radiation that arises due to
the temperature of a body. Most
energy of this type is in the infra-red region of the electromagnetic
spectrum although some of it is in the visible region. The
term thermal radiation is
frequently used to distinguish this form of electromagnetic
radiation from other forms, such as
radio waves, x-rays, or gamma rays. The transfer of heat from
a fireplace across a room in the
line of sight is an example of radiant heat transfer. Radiant
heat transfer does not need a medium, such as air or metal,
to take place. Any material that
has a temperature above absolute zero gives off some radiant
energy. When a cloud covers the
sun, both its heat and light diminish. This is one of the
most familiar examples of heat transfer
by thermal radiation.
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