All Questions
8
questions
0
votes
3
answers
95
views
Question on black body radiation
In black body radiation at thermal equilibrium, the absorptivity is equal to emissivity (to conserve energy). Is it fair to say that all of the photons falling on the body are absorbed and emitted? If ...
1
vote
1
answer
100
views
Apparent radiation pressure paradox
Imagine a plate beeing irradiated from all sides with a specific wavelength. One side of the plate is smoth and reflects most of the incoming radiation, the other side is covered in grooves with the ...
- 119
3
votes
1
answer
163
views
Why should Rayleigh-Jeans law hold for anything other than cavity radiation?
The Rayleigh-Jeans law is derived for a box with reflective walls. This system is designed to be able to accumulate electromagnetic radiation because of reflection for wavelengths that "fit in ...
- 631
4
votes
1
answer
220
views
Planck's catastrophe?
In deriving Planck's blackbody formula, the number density of normal modes (per unit frequency$^\dagger$) is found, given by
$$
N(\omega)=\frac{V}{\pi^2c^3}\omega^2,
$$
where $V$ is the volume of the ...
- 1,951
2
votes
1
answer
1k
views
Cavity Radiation, why should only standing waves persist in the cavity?
"Because when the box is in thermal equilibrium, there can never be any electric field at the walls for it would shake the charge in the wall around, changing the temperature, contradicting the ...
- 631
4
votes
2
answers
646
views
Two questions about the standing waves in a black body
I am currently reading a derivation of Rayleigh-Jeans law for cavity radiation from Eisberg and Resnick 1 . The authors derive the law by considering a cavity with metallic walls. In the book, the ...
- 1,324
2
votes
3
answers
525
views
Intuitive understanding of the derivation of the Rayleigh-Jeans law
I know the Rayleigh-Jeans law and how the formula predicts UV catastrophe. Without getting into the exact derivation, I am trying to get some intuitive understanding of it by using some of the broad ...
- 1,481
-2
votes
3
answers
460
views
How "things" radiate electromagnetic radiation? [closed]
How things radiate electromagnetic radiation? I don't ask why they radiate (higher temperature than 0K) but how they radiate this electromagnetic waves?
- 1,031