Questions
about blackbody radiation
1. How does object behave in when
impinge by visible light
2. What is a black body
3. is a good absorber of radiation a
good emitter
4. regarding the visible spectrum, what
is the relationship between color and wavelength?
A blackbody
is a surface that emit radiations at all wavelength of electromagnetic
spectrum, at all temperature and at all angle of incidence. It is an idealized
body that is regarded as a perfect absorber as well as a perfect emitter.
At a given temperature , a blackbody is one
that emits the maximum amount of energy
at each wavelength , with blackdody radiations
All substances with body temperature above the
absolute zero kelvin constantly emit energy in the form of radiations . The
radiant energy is usually transported by electromagnetic waves in accordance with classical electromagnetic
theory or alternately by photons in accordance
with quantum mechanics. In most cases the wave theory is frequently adopted for
explaining the radiation phenomenon in
spites of its shortcomings.
The nature of radiations is the same since it
require no carrying medium for propagations and it travels at the same speed as
light. The difference between one radiation to another only lies in its frequency
an wavelength which are related by c=fλ,
where c is the speed of light , f is the frequency and λ is the wavelength .
When an incident ray impinges on a body, part
of it is absorbed, reflected or transmitted depending on the nature of the
body. If the body is n opaque, most of the radiation will only be absorbed and
not reflected or transmitted, when the object is transparent most of the ray will be transmitted ,when the object
is translucent the light will be scattered, when the body is white most of the
ray will be reflected but when the body is black most of the ray will be
absorb.
Visible light
has colors and each color correspond to wavelength, all object
when exposed to visible light will only reflect the spectrum that
corresponds to its color but absorbed all other colors, for example a red
object will absorb all other spectra but reflect red colors of visible light, a
blue object will reflect blue spectra but absorb all other wavelength. A
black object will absorb all but reflect none of the spectrum of the
electromagnetic radiations while a transparent body will transmit all but
absorb nor reflect none of the wavelength
of the electromagnetic radiations. Or a blackbody will emit all but reflect none
of the spectrum of the electromagnetic radiations while a transparent body will
transmit all but absorb nor reflect none
of the wavelength of the electromagnetic radiations
Therefore a blackbody is a good absorber of
radiation and a good emitter.
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