How to Calculate the Fermi Wavevector from the Fermi Level?

[Toni103]

Note: I already asked this question ion the introductory physics forums but have had no replies.

The question I'm being asked is: If the Fermi level of copper is 7eV calculate the magnitude of the Fermi wavevector?The formula I'm pretty sure it goes with is Kf=(3pi^2ne)^2/3
The reason I'm unsure is when I looked it up I found conflicting information on what the variables stood for? I'm not looking for anyone to do the question or anything for me I'm just looking for help on what the variables stand for.

EDIT: Ok now I'm thinking the formula E = h(bar)^2k^2/2m would be better. Using this formula I've found the wave vector to be 1.359x10^10 which seems like an extremely large number. Is this right?

 

[kloptok]

Yup, that's what I get too.

Values for the wave vectors typically have very large values (around 10^13 m^(-1) ) in solid state physics so this is not an extremely large number in this context, I would rather say that it is a small value of a wave vector, considering that phonons typically have wavevectors with a magnitude of 10^13 m^(-1).

 

[Toni103]

Great thanks very much Kloptok! For some reason I thought I should be getting a very small number but I see with the equation now its actually the opposite.