(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

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.

2. Relevant 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 = p_{o}[1+α(T-T_{o})], where α = temp coefficient of resistivity at 20°C, p_{o}= resistivity at 20°C, and T= temp

I = nqAV_{d}

3. 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

V_{d}= 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

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# Homework Help: Drift speed question

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