# Continuous Charge Distributions

1. Jul 6, 2014

### WarpSpeedo

1. The problem statement, all variables and given/known data

A charge lies on a string that is stretched along an x axis from x = 0 to x = 3.00 m; the charge density on the string is a uniform 9.00 nC/m. Determine the magnitude of the electric field at x = 8.00 m on the x axis.

2. Relevant equations
$\int_0^3 kλ/(8-x)^2\,dx$
3. The attempt at a solution

k=8.99e9
λ=9

I know k and λ can come out of the integral leaving 1/(8-x^2). which gives me 9.44e-10 which webassign marks wrong.

2. Jul 6, 2014

### vela

Staff Emeritus
Your set-up looks fine, but I don't get anything close to the numerical answer you're getting.

3. Jul 6, 2014

### TSny

Are you thinking about the units for λ?

4. Jul 6, 2014

### WarpSpeedo

Problem was the units for λ. Thanks for your help