All Questions
Tagged with absorption radiation
23
questions
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2
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70
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Regarding the absorption property of a blackbody
Consider a blackbody of surface area $S_b$ and at temperature $T_b$. It is placed inside an evacuated chamber (to neglect all the effects of convection), with walls of chamber at temperature $T_c$ and ...
- 378
2
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1
answer
123
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Is a layer of gas with sufficiently large optical thickness really radiating as a black body?
Can a parcel of gas with large value of optical thickness really radiate like a black body?
I have in mind a simple (most likely oversimplified) model which yields
$$I_\nu = I_\nu(0) e^{-\tau\nu} + I_\...
- 1,299
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51
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How is black body radiation from sample eliminated when measuring absorption coefficient?
I wonder how absorption spectra of a sample (e.g. gas with some $CO_2$ absorbing strongly at $\approx 15\mu m$) is measured by IR spectroscopy, thereby having in mind the following arrangement, ...
- 1,299
2
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1
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876
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Why does water easily absorb THz radiation?
It is stated that water is extremely sensitive to THz radiation, absorbing big amounts of this radiation, this being a reason why skin measurements are safe to do using this range of frequencies (1) (...
- 753
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112
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Absorption of Beta decay and characteristic exponential absorption law
It has been discovered that Beta decays are a continuous spectrum of electrons and its absorption follows an exponential law with thickness of material (eg. Aluminium). This observation was often ...
- 3
1
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1
answer
482
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Thermal radiation vs emission spectra of gases
I am a high school student and I am very confused in absorption and emission spectrum of gases, for e,g take hydrogen at room temperature for simplicity, so that we can talk in terms of Bohr's model ...
- 470
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32
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Reconciling two descriptions of fluorescence
I am currently studying the textbook Infrared and Raman Spectroscopy: Principles and Spectral Interpretation, second edition, by Peter J. Larkin. Section 9. Selecting the Raman Excitation Wavelength, ...
- 889
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1
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138
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Emission of heat from absorption of light photon
So I've recently learned about photoelectric effect. It made sense at first, but when I try to combine it with what I thought I knew about emission and reflection of photon, things become rather messy....
- 95
3
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1
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160
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How does the attenuation coefficient of white light in water compare to the attenuation coefficient of monochromatic light in water?
So, from what I understand, different wavelengths of visible light, when shone through water, will have different attenuation coefficients due to scattering and absorption from the water molecules. ...
- 59
1
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1
answer
6k
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What happens to oxygen during atmospheric absorption of radiation with a peak at 60 GHz
This question discusses atmospheric absorption of radiation (specifically 5G radio waves) due to oxygen at 60 GHz.
I would like to know exactly what happens to oxygen in all its forms (be it air or ...
- 119
-1
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1
answer
134
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Are there anti-reflective paint other than black matt paint?
I am trying to build a box where I will be testing some materials inside the box to take measurements of the irradiation. I need to make it so that the walls of the box do not reflect any radiation (...
- 11
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1
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120
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Poynting vector interpretation
I am trying to calculate the dynamics of the power density of light in vacuum. The absorption per unit volume defined in terms of the Poynting vector is given by:
\begin{equation}
\text{Absorption} = -...
- 11
1
vote
1
answer
53
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Reduced absorption coefficient question
I came across a paper that reads
It is noteworthy that for a sample without lateral light propagation in the material, i.e. [reduced scattering] $\mu_s' = \infty$ and [absorption] $\mu_a=0$, ...
...
0
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2
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668
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White hotter than black
Black color substance is assumed to absorb all the light/radiation that falls on it. White color substance on the other hand, reflects all the radiation that falls on it. Since all the momentum of ...
- 133
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1
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163
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Are these statements about different emissivities correct?
I'd like to verify if my concluded statements regarding different emissivities are correct or not. And if not, why.
1
Two objects, one with an emissivity of 1 (object A) and one with a very low ...
- 471