- #1
tom_paine
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Homework Statement
I’m trying to find the drift speed of electrons in a copper wire. The length of the wire is 10 meters, temp is 60°C, current is 5 A and the total resistance of the wire is 0.05 ohms.
Homework Equations
# of charge carriers (n) = density * 6.02 x 10^23/molar mass
R = pL/A, where p = resistivity of the wire, L = length and A = area
p = po[1+α(T-To)], where α = temp coefficient of resistivity at 20°C, po = resistivity at 20°C, and T= temp
I = nqAVd
The Attempt at a Solution
n = (8920 kg/m^3)(6.02 x 10^23)/(0.0635 kg/mol)
n= 8.5 x 10^28
p = 1.7 x 10^-8 [1 + 3.9 x 10^-3(60-20)]
p= 2.0 x 10^-8
Area = pL/R
= 2.0 x 10^-8 * 10/0.05
= 4 x 10^-6
Vd = I/nqA
= 5/(8.5 x 10^28 * 1.6 x 10^-19 * 4 x 10^-6)
= 9.2 x 10^-5 m/s
I just want to know if I’m on the right track.
Thanks,
Tom