(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The thermal conductivity of Cu at room temperature is 400 W/(mK). Use this value to determine the average time between collisions, [itex]\tau[/itex]. Compare this value with the electrical conductivity.

2. Relevant equations

Not sure. I take T=300K for room temperature.

From a book and with little algebra, [itex]\tau = \frac{3 \kappa }{C_e \overline v ^2}[/itex]. Where [itex]C_e=nc[/itex], the specific heat of the electrons per volume unit. [itex]\overline v =<v^2> [/itex].

Also, [itex]<v^2>=\frac{3K_BT}{m_e}[/itex] and apparently [itex]C=\frac{3}{2}n k_B [/itex](they do not state what n is, but I think it's the electronic density because they said that c is the specific heat per electron)

3. The attempt at a solution

Using only the given data, I do not see a clear way to solve the problem, it seems like a data is missing (for example the electron density). Am I missing a way to solve the problem?

If I had "n", I'd be done, because [itex]\tau = \frac{2\kappa m_e }{3nk_B^2T}[/itex] and everything is known but n.

I guess I'm missing something obvious, yet I don't see it. Thanks for any help.

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# Homework Help: Estimating the average time between collisions (electrons in Cu solid)

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