Answer on Question #51560, Physics, Solid State Physics
Aluminium has three valence electrons per atom, an atomic weight of 0.02698
kg·mol−1, a density of 2700kg·m-3, and a conductivity of 3.54× 107 W−1m−1.
Calculate the relaxation time in Aluminium.
Solution
Boltzmann transport equation in the relaxation time approximation leads to the
conduction electron gas to the Drude formula:

n  e 2 
2me
(1)
 - Electrical conductivity; n  3   N A /   3   2700  6.02  1023  / 0.02698  1.81 1029 m3 -
electron density; e  1.6 1019 C  1.6  1019 A  s - elementary charge; - the momentum
relaxation time (the time at which the electron "forgets" about which way to go);
me  9.11031 kg - the effective mass of the electron.
Then

Answer:  
2me 2  9.11031 kg  3.54 107 W 1m1

 1.4 1014 s
2
2
29

3

19
ne
1.8110 m  1.6 10 C 
2me
 1.4 1014 s
2
ne
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