All material change colour with temperature. Each colour is associated with
a different temperature, independent of the material. This phenomena is know
as black body radiation. Radiation occurs because the body is hotter than
its surroundings. The energy captured by the body promotes the body's
electrons to a higher orbit. When the electrons jump back to a lower orbit,
a photon is release. The lower orbits are more desirable (lower potential
energy) to the electron and thus it will eventually jump back down. Note:
not all photons exist in the visible light region of the electromagnetic
Thermionic emission is due to the emission of electrons at high
temperatures. Thus the difference between thermionic emission and black body
radiation is the particle used to transfer the energy. Photons are radiated
in black body radiation and electrons are emitted in thermionic emission.
Both are ways of transferring energy from a high temperature reservoir to a
low temperature reservoir.
Ask a Scientist:
The intensity of the emitted light is a function of the frequency of the
radiation and the temperature. So, I guess you might say that an object is
emitting all wavelengths, but it only becomes visible when it reaches a
certain temperature, the intensity is sufficient to stimulate the retina in
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