Thermal Conductivity for metals

[Dhesi]

For my advanced higher physics investigation I've been given the topic of thermal conductivity.

Basically I am going to investigate the thermal conductivity of different metals and compare them to the electrical resistance of the metal as I believe that those with low electrical resistance will be good conductors of heat.

I've also been told to find out about the Weidmann-Franz ratio as this is another factor which I can investigate. Searching google hasnt really helped so could someone please give me a bit more information on this?

Thanks,

Michael

 

[marcusl]

For my advanced higher physics investigation I've been given the topic of thermal conductivity.

Basically I am going to investigate the thermal conductivity of different metals and compare them to the electrical resistance of the metal as I believe that those with low electrical resistance will be good conductors of heat.

I've also been told to find out about the Weidmann-Franz ratio as this is another factor which I can investigate. Searching google hasnt really helped so could someone please give me a bit more information on this?

Thanks,

Michael

You can start off by learning about the role conduction electrons play in electrical and thermal conductivity, then at the role phonons and scattering play in resistivity. Have you taken quantum mechanics? I'm assuming yes since the Wiedemann-Franz law is based on the concept of an electron gas. Check out Kittel, Introduction to Solid State Physics for a good intro treatment, complete with experimental data. Many people prefer the older editions (I have the 3rd). From there you can move up to a rigorous treatment of transport and scattering (Boltzmann equation, etc.) in one of the classic books on solid state, e.g., Ziman or Ashcroft and Mermin. Harrison, Solid State Theory (Dover pub) is among them and has the advantage of being very inexpensive.

A related thermal/electrical ratio is the Lorenz number.

 

[Dhesi]

Hi,

Thanks for the response. Unfortunately I am not a university student I am in my last year of high school and the course we do is similar to that of first year university, but sadly I don't have the book you're referring to. This is an investigation we do where you are given a topic a bit outwith the bounds of the course to see how you handle it. Just couldn't find many resounrces online about it.

 

[marcusl]

Ah, that changes things. Take a look instead at
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/thercond.html"
for a general description. This site (called "hyperphysics") is an excellent place to start research on a physics topic.

I'll look around tonight for any other sites that might work for you.

 

[Gokul43201]

First understand the Drude derivation for the conductivity: http://hyperphysics.phy-astr.gsu.edu/hbase/electric/ohmmic.html#c1

Next, using the expression for electronic heat capacity, and the relationship between electronic thermal conductivity and heat capacity, you can write down an equation for the thermal conductivity of a metal.

Finally, taking the ratio of the two gives you the form of the Wiedemann-Franz Law: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/thercond.html#c2

PS: Marcusl beat me to it.

 

[marcusl]

PS: Marcusl beat me to it.

We thought alike but I typed faster!

Here's another site that looks reasonable, with short descriptions of the major concepts and few equations.
http://www.answers.com/topic/free-electron-theory-of-metals"
Read the top half and click on Conductivity (electric and thermal), Mean Free Path, and W-F Law. (The second half is more advanced; it does mention lattice vibrations and phonons towards the end).

For the flip side to conductivity, see
http://www.answers.com/topic/lattice-vibration"
and the link on electrical resistivity.

 

[Dhesi]

Really appreciate the help, I am much more clued up now :)