Homework Help: Coulomb Constant Question

1. Feb 6, 2008

Old Guy

1. The problem statement, all variables and given/known data
I'm sure I'm missing something simple here, but to the point:

I calculate the electric field a distance r from a uniform straight infinite line charge using Gauss' Law and get an answer; I do the same calculation using Coulomb's law and get the same answer but a pi remains in the denominator (that was not there in the Gauss' Law solution). I don't know how to enter the equation here, but in both answers the numerator is the linear charge density. The Gauss' Law denonminator is 2r times epsilon; Coulomb's law denominator is 2(pi)r times epsilon. Help!

2. Relevant equations
See above

3. The attempt at a solution
See above

2. Feb 6, 2008

foxjwill

Can you write out each of your steps? Maybe then one of us'll be able to spot the error.

3. Feb 6, 2008

Old Guy

Well, thanks for the fast response. In writing out the steps as you requested I caught a (dumb) integration error - I'm straight now. Thanks.

4. Feb 6, 2008

foxjwill

You can't imagine how many times I've been stumped on a problem only to realize my error while explaining what I did to someone. :)