compare electricity to heat

[lemur]

Negative voltage is not directly comparable to negative temperature. Voltage measures a comparative value (potential difference), whereas temperature is an absolute value.

If I am correct, electric current is an entropic process comparable to heat-disequilibrium where it is charge instead of temperature that is moving toward equilibrium. Voltage, I thought, refers to the strength of the current due to the level of charge disequilibrium between the electrodes. Temperature, I think, is a measure of average kinetic energy among the particles of a system or part of a system. So I think that temperature would be more like charge and voltage would be analogous to what? Is there a term for rate of heat transfer? Can it be negative except in the sense of the direction changing?

[Schrödinger's hat]

Umm, I'm not sure this is a great thing to make analogies between, but here goes:

Voltage could be compared to temperature difference between source and destination. Where potential measures concentration of potential energy, temperature measures concentration of heat energy.

The word you're looking for is thermal flux, which is equivalent in some ways to current, and in some ways to power of a circuit.

 

Negative temperatures can in some ways be defined, but it involves a lot of quantum and isn't related to definitions based on average kinetic energy. So, negative temerature doesn't exist in the way you're thinking. You could have negative temperature difference the same way you can have negative potential difference.

 

Another important difference is heat is always positive (you can only gather heat together, and it will want to spread out into its surroundings). Whereas charge has two signs (an electron and a proton will attract.

As I said, it's possibly not a good idea to try and make an analogy between these types of systems. Especially as you go into more detail about thermodynamics/stat mech.

[Mr Skeptic]

In case you're wondering, -10 degrees F is a positive temperature.

[lemur]

Umm, I'm not sure this is a great thing to make analogies between, but here goes:

Voltage could be compared to temperature difference between source and destination. Where potential measures concentration of potential energy, temperature measures concentration of heat energy.

The word you're looking for is thermal flux, which is equivalent in some ways to current, and in some ways to power of a circuit.

 

Negative temperatures can in some ways be defined, but it involves a lot of quantum and isn't related to definitions based on average kinetic energy. So, negative temerature doesn't exist in the way you're thinking. You could have negative temperature difference the same way you can have negative potential difference.

 

Another important difference is heat is always positive (you can only gather heat together, and it will want to spread out into its surroundings). Whereas charge has two signs (an electron and a proton will attract.

As I said, it's possibly not a good idea to try and make an analogy between these types of systems. Especially as you go into more detail about thermodynamics/stat mech.

I'm not sure what kind of "more detail" you're talking about. Your post has got me thinking about the difference between energy-concentration (heat) differentials and charge differentials between positive and negative ions. Since heat is literally kinetic energy, it is different than charge, which is potential energy since it is a force-attraction or repulsion, right? On the other hand, having a concentration of negative ions is like having a pressurized system of electrons, right, whereas the positive ions would be like a low-pressure system of electrons (relative electrostatic vacuum?). So it is as if electron pressure is dissipating through the conductor to attain charge-equilibrium. This seems directly analogous to, say, a pressurized container being allowed to evacuate into a vacuum-pumped container; but can it also be analogous to a container of hot material being allowed to conduct heat through a wire into a heat sink of cold material? In a sense, I would say yes because of a vague association between heat and pressure, but since heat is technically molecular motion regardless of volume/density and pressure/density is only really directly related to heat in gasses, I'm not sure. I wonder if there is some validity in considering heat within a solid or liquid that's not melting or evaporating as pressure within the confines of the substance. In that sense, you could say a hot substance has a higher concentration of pressure-energy in the same sense as a pressurized gas, only the pressure is naturally contained by the phase-state of the particular substance. This in turn raises the question of whether ionization is akin to a phase-state of electrons, but that would mix up the configuration of the atoms/molecules with that of their surplus charge.

 

 

 

[swansont]

In case you're wondering, -10 degrees F is a positive temperature.

 

Mind = blown

 

 

jk

[Schrödinger's hat]

Lemur, your analogy works fairly well, up to a certain level, but thinking of heat as molecular motion is a concept that breaks down after a while. As do all analogies.

You start to have to consider the change in the values of energy levels, versus the change in distribution of particles with respect to these energy levels.

 

If you want to understand further you're going to have to study statistical mechanics and/or quantum physics for a while. Someone who has studied longer than I may be able to explain/translate these concepts better than I can, but there is always going to be a limit to what you can understand by going about it in this way.