# Homework Help: Average Electron Drift Distance with AC Current

1. Sep 14, 2015

### achap6

1. The problem statement, all variables and given/known data
A metal wire with 1023 free electrons per cubic centimeter is carrying 60 Hz alternating current with a maximum current density of 100 amps/cm2.
a) Write an expression for the average electron drift velocity as a function of time (vd as a function of time).
b) What is the average drift distance of free electrons in one direction in a half-cycle of current?

2. Relevant equations
J = σE = σEsin(ωt)
ω = 2πν
J = -eNevd

3. The attempt at a solution
Part a:

J = -eNevd
-eNevd = σEsin(ωt)
vd = (-σEsin(ωt)) / (eNe)

Part b:

Need help here, I attempted to plug in ω = 2πν into the equation J = σEsin(ωt), but don't seem to be getting anywhere, because I don't have σ or E.

Last edited: Sep 14, 2015
2. Sep 14, 2015

### Hesch

Calculate the average absolute current density ( [ A/cm2 ] ).

Calculate the amount of coulombs moved per second.

Calculate the amount of centimeter wire-electrons is moved per second.