How does the Surface of an Object
Affect the Absorption and Emission of Infra-red Radiation?
An object with a matt
(dull) surface will absorb and emit
infra-red radiation at a faster rate than an object with a shiny surface.
An object with a dark surface will absorb and emit
infra-red radiation at a faster rate than an object with a light surface.
Radiation is also reflected at the surface.
Imagine a hot piece
of metal which has a matt black surface
and a shiny white surface.
A thermometer is placed at the same distance from both surfaces.
The thermometer next to the matt
black surface shows a
higher temperature because it emits radiation at a faster rate.
Heat leaves the metal more quickly through
the matt black surface than the shiny white surface.
Part of the space shuttle is covered in matt black tiles.
These help the craft to lose heat from its surface when
it re-enters the Earth's atmosphere on returning from space.
The space shuttle gets very hot in the
Earth's atmosphere in the same way that meteors do.
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