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6 votes

Why Free-Free emission is regarded as Thermal emission?

Thermal radiation $\neq$ blackbody radiation. Thermal radiation is radiation that comes from a system where an equilibrium has been reached, where the various energy states are occupied according to ...
ProfRob's user avatar
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3 votes
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Meaning of critical density in radiative transfer

Your misunderstanding is in the second paragraph. If $n<n_c$ then there are insufficient collisions to excite the molecule into the upper level. Thus in equilibrium there are very few excited ...
ProfRob's user avatar
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3 votes
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Scattered Intensity of Light vs Angles of Incidence and Emission

It is easiest to understand if you fix the incident angle and explain why the emergent intensity is largest at highly oblique angles. Since the light comes from the outside, it only penetrates so far,...
Ken G's user avatar
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3 votes
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What is main radiative mechanism in Gunn-Peterson effect?

The Gunn-Peterson trough is a feature in the spectrum of a (background) source near the Lyman $\alpha$ line, caused by a high density of intervening, neutral hydrogen (HI). The background source may ...
pela's user avatar
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2 votes

How are absorption cross sections calculated?

In the case of the solar interior, where very often the physical conditions cannot be experimentally reproduced, the cross-sections are often calculated by the application of the relevant quantum ...
ProfRob's user avatar
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1 vote

Relation between intensity of Sun and the light that is emitted from surface of sun

We take a unit area dA of sun,, which is emitting light directly to our line of sight You are, I think, imagining the light as if it was directed out from a point, with directions of photons outward ...
StephenG - Help Ukraine's user avatar

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