
#1
Feb1912, 04:42 PM

P: 196

1. The problem statement, all variables and given/known data
The atom [itex]He^3[/itex] has spin 1/2 and is a fermion. The density of liquid [itex]He^3[/itex] is [itex]0.081g/cm^3[/itex] near absolute zero. Calculate the Fermi energy [itex]\epsilon_F[/itex] and the Fermi temperature [itex]T_F[/itex] 2. Relevant equations [itex]\epsilon_F = \frac{\hbar^2}{2m}(\frac{3 \pi^2 N}{V})^{2/3}[/itex] [itex]T_F = \frac{\epsilon_F}{k}[/itex] 3. The attempt at a solution In the problem I'm given the density is [itex]0.081g/cm^3[/itex], which is my N/V. Assuming that m is the mass of [itex]He^3[/itex], then [itex]m = 5.008*10^{24}g[/itex]. I should then be able to do a straight forward plugnchug; however my units don't work out as I get: [itex]\epsilon_F = \frac{\hbar^2}{1.0016*10^{23}g}(3 \pi^2 0.081g cm^{3})^{2/3}=1.99*10^{50} kg^{5/3} m^2 s^{2}[/itex] Clearly, this is not a unit of energy. What am I doing wrong? 



#2
Feb1912, 08:25 PM

P: 196

I need to use number density, rather than straight density. Which should take care of my problem.



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