Under simular conditions what is the amount of thermal noise in conductive liquids compared to metals
Consult the paper by AJ van den Berg, A de Vos, and J de Goede (Phys. Lett. A 139, 249 (1989)) and the references therein. Briefly, in micro-capillaries and under the condition of constant current, the noise consists of the Johnson-Nyquist noise, as in solid metallic conductors, and some excess noise arising from thermal fluctuations and the fluctuations in the number of ions.
https://doi.org/10.1016/0375-9601(89)90149-7
Thank you Mr. Farid for responding to my question. If I understand correctly, in the abstract it's saying that in addition to the Johnson-Nyquist noise there is another though "smaller contribution "to the thermal noise total, is that correct?. This other thermal noise contribution is said to be due to the fluctuations of " ions " in the sample. If fluctuations of the ions in the sample do contribute to the thermal noise then if a similar test were performed using a non polar (non-ionic) solution then would that not result in a lower thermal noise total?
Your are welcome Don.
The short answer to your question is yes. The noise coming from essentially independent sources, they are to leading order uncorrelated, so that there is no cross-correlation term; the mean-square currents*) are therefore additive (consult the attached page).
*) See, for instance, JB Johnson, Phys. Rev. 32, 97 (1928).
http://muchomas.lassp.cornell.edu/8.04/Lecs/lec_statistics/node14.html
Mr. Farid ,
I have another question if I may. At RT is the Black Body radiation frequency the same for a Solid and a Gas. Do their volumes have to be the same for the Black Body radiation frequency to be the same?
Generally, to photons one can attribute a spectral distribution. To obtain this, one has to solve the radiation problem in the system under consideration. The radiation eigenmodes of the system contribute to this spectral distribution. Ordinarily, one solves this radiation problem in a uniform system subject to a convenient boundary condition (e.g. the box boundary condition). In the absence of matter (i.e. classical vacuum) and in a uniform background, the energy dispersion of photons has a simple form (a linear dispersion whose slope is determined by the speed of light in vacuum), but this is not the case in general. In a solid (such as regular crystals), electromagnetic modes and their energy dispersions take complicated forms. For this, consider any good book on solid state physics and search for polaritons. The book by Ashcroft and Mermin is one, and that by JJ Quinn and S-K Yi is another -- Solid State Physics (Springer, Berlin, 2009).
You provided some information for a vacuum and a solid but you didn't elaborate about a gas. I'm mainly interested to know if the black body radiation in a gas is changed as the said gas is subjected to a gradually increasing pressure!
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