
Show that the claims made in the backbone text are actually true (for room temperature = 300
K). Use the following equations taken from the backbone 


For the average velocity v_{0}
of a particle zooming around in the crystal: 


v_{0}  =  æ ç è
 3kT m 
ö ÷ ø  1/2 




For the mean time t
between scattering: 
 



For the drift velocity v_{D} 
 



For the minimal mean free path length
l_{min} obtained for v_{D} = 0: 
 


Of course, you need numbers for the concentration n of the free carriers and
for the specific conductivity s 


Since we are essentially considering metals, you assume for a start that you have 1
free electron per atom if you want to find a number for n. Here are a few data needed for the calculation: 
 
Atom 
Density [kg · m^{–3}] 
Atomic weight × 1,66 · 10^{–27} kg 
Conductivity
s × 10^{5} [W^{–1} · m^{–1}] 
Conzentration Atoms n [m^{–3}] ??? 
Na 
970  23 
2.4  
Cu 
8.920  64 
5.9  
Au 
19.300  197 
4.5  


You may run into some trouble with the dimensions. Just look at conversions from, e.g. [eV]
to [J], from W to V and A, and at the relations beween Volt, Ampere,
Watts and Joule. 
 