All Questions
Tagged with equilibrium thermal-radiation
21
questions
2
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1
answer
49
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Two interacting blackbodies (one inside another) - when will thermal equilibrium be attained? [closed]
As I understand it, an ideal blackbody absorbs (and subsequently starts emitting) all incoming radiation. In typical setups like determining a planet's temperature given its albedo and distance from a ...
- 35
1
vote
2
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67
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How do differently colored objects reach the same temperature if they are completely isolated together?
Imagine a perfectly reflective container, filled with vacuum and two bodies with different colors, i.e. they have different emissive and absorptive properties. The bodies don't touch each other or the ...
- 13
0
votes
1
answer
68
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Can a body be in thermal equilibrium at a different temperature from surroundings?
As per my knowledge bodies attain constant temperature (thermal equilibrium with surroundings) when they absorb and emit energy at equal rates.
Let us say temperature of surroundings is T1.
We have a ...
- 1
0
votes
2
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78
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Would a black teapot midway between the temperatures of the tea and air cool down or heat up? If neither, then how do the 3 reach thermal equilibrium? [closed]
Say you had a matt black teapot with hot tea inside it but cool air around it. Originally, I’m guessing the matt black teapot should absorb more joules of IR energy than it emits per second. This is ...
- 115
0
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1
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302
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Equilibrium in blackbody radiation
I was reading this post and I think I am still confused. A blackbody $radiator$ is not in equilibrium, by definition, since it is radiating. If so, why does the blackbody spectrum accurately describe ...
- 1,647
0
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165
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On the calculation of the radiation from a gray body
To my understanding, nearly all results obtained on thermal radiation are based on two requirements: thermal equilibrium and more importantly, radiative exchange equilibrium. Only in the case of no ...
- 339
4
votes
3
answers
498
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Why does the spectrum of Sun follow a black-body distribution curve?
Black-body radiation, as I understand it, is radiation in thermal equilibrium at a fixed temperature with a cavity. The spectrum of such radiation follows the famous black-body distribution curve. But ...
- 11.8k
0
votes
1
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182
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Equilibrium temperature of a black body when the volume of the black body is changed
If a black-body is at an equilibrium temperature T of a certain volume. If we increase size of blackbody does the equilibrium temperature of the blackbody will change?
- 317
3
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3
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288
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How long does it take for an electron to reach equilibrium with blackbody radiation?
While teaching a course on electrodynamics, I thought of an interesting question that I think deserves some attention.
Consider an ensemble of electrons all with momentum $\hbar \mathbf{k}$ traveling ...
- 7,931
2
votes
1
answer
124
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Local equilibrium of slow time varying thermal system
I'm trying to differentiate a thermal system in local equilibrium (and slow time varying) v/s a non-equilibrium system.
For a thermal system which is slowly time varying, how does one define local ...
- 1,023
1
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1
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357
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What does blackbody radiation look like for negative-temperature systems?
Using the thermodynamic definition of temperature,
$$\frac{1}{T}=\frac{\partial S}{\partial U}\bigg|_{V,N}$$
negative temperatures are possible, in systems where the entropy decreases when energy is ...
- 35.6k
0
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2
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1k
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Thermal equilibrium vs steady state
According to Kirchhoff's law, when two objects are in thermal equilibrium, both objects have the same temperature and each object emits as much energy as it absorbs. Also, the energy absorbed at each ...
- 93
1
vote
1
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335
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If photon decoupling was a departure from equilibrium why does CMB exhibit a blackbody spectrum?
Decoupling of photons from the cosmic plasma or thermal bath is said to be a point of departure from thermal equilibrium. But we know that the cosmic microwave background (CMB), consisting of the ...
- 26.8k
1
vote
1
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993
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Prevost Theory of Exchange
I am having a trouble in understanding this concept.
If bodies are at thermal equilibrium, there is no heat transfer.
Heat is transferred through three different ways: Conduction, convection and ...
- 27
3
votes
1
answer
401
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If the fundamental definition of thermal equilibrium is no net heat transfer, how does one derive that temperatures must be equal?
The following thought experiment will help understand my confusion. Note that I'm only considering thermal equilibrium in the context of radiation heat transfer.
Let's consider an oven which is an ...
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