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All objects v a temperature over absolute zero (0 K, -273.15 oC) emit energy in the type of electromagnetic radiation.A blackbody is a theoretical or version body i m sorry absorbs every radiation fall on it, reflecting or transmitting none. The is a theoretical object which is a “perfect” absorber and also a “perfect” emitter that radiation over all wavelengths.

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The spectral distribution of the thermal energy radiated through a blackbody (i.e. The pattern of the intensity of the radiation over a range of wavelength or frequencies) depends only top top its temperature.


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Blackbody radiation curves at several different temperatures.Credit: julianum.netburne

The qualities of blackbody radiation can be described in state of numerous laws:

1. Planck’s Law that blackbody radiation, a formula to identify the spectral energy density of the emissions at each wavelength (Eλ) at a specific absolute temperature (T).

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2. Wien’s Displacement Law, which says that the frequency that the optimal of the emission (fmax) increases linearly v absolute temperature (T). Conversely, together the temperature of the body increases, the wavelength at the emission height decreases.

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3. Stefan–Boltzmann Law, which relates the total power emitted (E) come the pure temperature (T).

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In the photo above, an alert that:

The blackbody radiation curves have quite a complex shape (described by Planck’s Law).The spectral profile (or curve) in ~ a particular temperature synchronizes to a specific peak wavelength, and vice versa.As the temperature the the blackbody increases, the top wavelength reduce (Wien’s Law).Although the intensity might be very low at really short or long wavelengths, at any kind of temperature above absolute zero power is about theory emitted in ~ all wavelengths (the blackbody radiation curves never reach zero).

In julianum.net, stars are frequently modelled as blackbodies, although that is not constantly a good approximation. The temperature the a star have the right to be deduced from the wavelength the the height of that is radiation curve.

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In 1965, the cosmic microwave elevator radiation (CMBR) was uncovered by Penzias and also Wilson, who later won the Nobel prize for your work. The radiation spectrum to be measured by the COBE satellite and also found to be a impressive fit to a blackbody curve with a temperature that 2.725 K and also is interpreted as evidence that the universe has been expanding and cooling for about 13.7 billion years. A much more recent mission, WMAP, has actually measured the spectral details come much greater resolution, finding small temperature fluctuations in the early Universe which eventually led come the large-scale structures we check out today.