"Heat current" on a microscopic level

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Discussion Overview

The discussion centers on the differences between electric current and heat current at a microscopic level, exploring concepts related to the transport of charge versus the transport of energy. Participants delve into theoretical aspects, mathematical descriptions, and the underlying physics of these phenomena.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that electric current involves the transport of electric charge, while heat current involves the transport of heat energy.
  • It is mentioned that electric current results in the flow of charged particles (electrons) and can produce magnetic fields, whereas heat current is characterized by a flow of kinetic energy without overall transport of particles.
  • One participant suggests that there may not be a significant difference between electric current flow and energy flow, particularly when considering charge balance in conductors.
  • Mathematical analogies are drawn between electric current density and heat current density, with references to Ohm's law and Fick's law, indicating a potential correspondence between the variables involved.
  • A question is raised regarding the nature of caloric and its relation to charge, prompting further inquiry into the definitions and assumptions surrounding heat and electric currents.

Areas of Agreement / Disagreement

Participants express differing views on the depth and clarity of the original question, with some suggesting that the distinctions between electric and heat currents may not be as pronounced as initially thought. The discussion remains unresolved regarding the fundamental differences and similarities between the two types of current.

Contextual Notes

Some participants highlight the need for clearer questions to facilitate deeper understanding, indicating that assumptions and definitions may play a significant role in the discussion.

zb23
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What is the difference on microscopic level between electric current and heat current(conduction)?
 
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Electric current describes a transport of electric charge and the heat current a transport of heat energy.
 
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It may be of interest that with electric current, there is a flow of charged particles, (electrons in the direction opposite the current flow), and the result is magnetic fields are produced (Biot-Savart), and capacitor plates can become charged.
With heat current, there is no overall transport of particles. It is simply a flow of the kinetic energy.
 
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vanhees71 said:
Electric current describes a transport of electric charge and the heat current a transport of heat energy.
Please understand my question more deeply
 
Then you have to more clearly express your question :-).
 
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Charles Link said:
It may be of interest that with electric current, there is a flow of charged particles, (electrons in the direction opposite the current flow), and the result is magnetic fields are produced (Biot-Savart), and capacitor plates can become charged.
With heat current, there is no overall transport of particles. It is simply a flow of the kinetic energy.
I am not talking about those trivial stuff
 
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vanhees71 said:
Then you have to more clearly express your question :-).
It doesn't matter. Sorry for bothering you.
 
zb23 said:
I am not talking about those trivial stuff
It seems like a good question you asked. Without the details of the "trivial stuff", there perhaps isn't much difference between electric current flow and energy flow.
e.g. if the charge balances in the conductor carrying current, how do you know that there is a flow of charge as opposed to a flow of energy/heat ?
 
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Mathematically the description of each isn't too different. For electric current one case you could consider is where Ohm's law holds i.e. the electric current density can be shown to satisfy$$\mathbf{j}_e = -\sigma \nabla \phi$$For heat current, if you assume that there is no convection component (i.e. if we assume there is only a Fick's law diffusion component) to the heat current density, you can describe it as$$\mathbf{j}_h = -D\nabla T$$In this way there is a correspondence between ##\phi \leftrightarrow T## and ##\sigma \leftrightarrow D##
 
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Caloric does not carry charge?o_O
 
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zb23 said:
Please understand my question more deeply
Please put more effort into your question. The answer you got was the answer to the question you asked. We cannot read your mind, so we don’t know what deep question you are asking unless you put in the effort to formulate it clearly and write it down. All we can do is respond to what you write. We are physicists, not psychics.
 
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