Is thermal conducticity realated to electrical conductivity?

[aznmist]

Is thermal conducticity realated to electrical conductivity?

 

[Passions]

As thermal energy goes up, so does electron movement. Bonds are broken and electrons can flow to the conduction band. So yes.

 

[Einz]

uhh, i thought thermal conductivity and electrical are two separate things? i think bobby ribs is talking about temperature and electrical conductivity. anyways, arctic silver ii has one of the best thermal conductivities and it does not conduct electricity at all. just my 2 cents.

 

[conker]

Not necessarily so. There are many materials, especially the new ceramics, which have excellent thermal conductivity, but no electrical conductivity. Thermal and electrical conductivities are mostly related to metals e.g. copper and aluminum etc.

 

[Bleep]

Let me blow your mind a little here. Water--ecxellent thermal conductivity and the best insulator or the least conductive electrical. Water is rated at 0 on the electrical conductivity and all other electrical insulators are rated against it.
Bleep

 

[Jiggz]

Bobby was talking about temp against electrical conductivity which is quite correct. But on the question of thermal conductivity and electrical conductivity, there may be a little relation but not entirely. Aluminum is a good conduct of electricity and also with heat. Copper is a better conductor of electricity compare to Al and is also a better heat conductor. On the otherhand, Silver and Gold are the best electrical conductor but not as thermal conductor. Other ceramics are electrical insulators but yet they are often good thermal conductors. So where the relation is I'm not sure. I believe its material has it's own thermal and electrical conductivity characterisitics.

 

[kingz]

I read (I think in my AP Chem book) that diamonds are one of the best thermal conductors. Its also a great insulator. Is that correct? I don't really remember, so someone please refresh my memory

 

[kornermi]

Higher temperature, more carriers in conduction band, so higher electrical conductivity. That's true, but this explanation only applies to semiconductor, doesn't it? Furthermore, if the temperature continues to rise, electrons experience more collision while they move, so actually, the conductivity goes down.

In case of metal, which already has plenty of free electrons, number of electrons is not really a limiting factor. I doubt hotter aluminum conducts electricity any better than cooler aluminum.

 

[Dark4ng3l]

Hmmmm I learned that electric cunductivity went up as the temperature of the conductor went down and that heating it up lowered the electric cunductivity.

 

[Mark R]

The effect of temperature on electrical conductivity varies from material to material - while metals conductivity falls with increasing tempeature, many semiconductors can show the opposite effect.

In metals, thermal conductivity is related to electrical conductivity because the same mechanism accounts for both - but as has been pointed out earlier, in ceramics and other substances heat transfer occurs via mechanisms which do not permit electrical transfer.

Finally a small correction, water is actually a very poor conductor of heat - however convection within the liquid greatly helps heat transfer. Try a little experiment - get a test tube fill it with water. Take some ice which has been weighed down with steel shot and put it in the tube so that it sinks - heat the top of the tube until the water boils. See how long it takes for the ice to melt.

 

[yaethom]

<< Water--ecxellent thermal conductivity and the best insulator or the least conductive electrical >>



That is definitley wrong, water is NOT an excellent thermal conductor. In fact its one of the worst ones. That is why they use water to put out fires, cool down cars, etc. Now you may think it is a good conductor because they use it for all these cooling applications, but u have to keep in mind they use COLD water to cool the stuff down. Water is in fact very hard to heat up and very hard to cool down. Its one of the worst heat conductors out there.

And to the original question, electrical conductivity and thermal conductivity and no specific relation to each other. (Don't get that confused with: as the heat goes up, electrical conductivity goes down) Because that has no relation with the heat conductivity of the material.

When u think of metals, you might say that heat conductivity is related to electrical conductivity. But you also have to remember that Gold is the best room temperature conductor, and yet it is definitely not the best heat conductor. While other materials such as salt water, is an excellent conductor, but its one of the worst heat conuctors. I'm sure that will clear up this thread.

 

[aznmist]

yaethom: but what about super conducters? metals and ceramics seem to show the properties of supercoducters when the temps is near absoloute zero

 

[yaethom]

yeah, but superconductors are a completely different story.

In fact, the best conductors are usually pretty bad super conductors.
And the future of material science is based on finding materials that superconduct at extremely high temperatures. (meaning close to room temperature).
Superconductivity really does not apply to the computing world yet, simply because there is no industrial use for such, since they are too expensive to maintain. The only real uses of superconductors now are in fusion reactors and MRI's. (the superconductors are the magnets in those things)

And you have to remember, that superconductivity doesn't apply to electrical conductivity at all, it is just an example of how electrical conductivity changes when temperature changes. (and since it really is off topic from the basic physics world, superconductivity really has very little in common with normal conductivty)

Tom

 

[zzzz]

Thermal conductivity is related to movement (vibrational) of atoms in molecules or crystals. The crystal vibrational modes are called &quot;phonons&quot; in analogy to electrons. ( As electrons carry charge, phonons carry thermal energy, There are many &quot;ons&quot; in physics. These quasi-particles are based on the methods used to calculate the properties but I digress)
Electrical conductivity is related to movement of electron.
So these two are unrelated.

 

[jamarno]

Does water conduct heat better than beryllium oxide, which conducts heat about as well as pure aluminum but is an electrical insulator (and highly toxic)?