# Homework Help: The speed of the electrons in the conductor

1. Aug 23, 2009

### gabor7896

1. The problem statement, all variables and given/known data
A copper conductor with a cross-section of A and a lenght of is connected to a battery with a electromotive force of U. The resistance of the conductor is R, and the internal resistance of the battery is negligible.
U = 220 V
l = 10 m
A = 10 mm2
R = 0.01695 $$\Omega$$
Determine the average speed of the electrons!

3. The attempt at a solution
I know the electric current. But I have no idea how many electrons are moving.

I'm not a native speaker. I may have grammer mistakes.

2. Aug 23, 2009

### Engels

I will give u all the equations u need(i think) and try to solve it by urself

I=dQ/dt
dQ=nqvAdt thus I=nqvA n is the charge concentration, v the electrons velocity, A surface area

J=I/A J is the current's density

v=J/nq

hope i helped

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