# Potential Difference b/t 2 points

1. Jul 13, 2006

### rjnara

Ok, I've got a problem:

The electric field in a region of space has the components Ey = Ez = 0 and Ex = (3.91 N/C)x. Point A is on the y axis at y = 2.83 m, and point B is on the x axis at x = 3.97 m. What is the potential difference VB - VA?

I have tried integrating E (wrt x) * x from x=0..3.97 . I keep getting 81.5506, and its not the right answer. Anyhelp would be appreciated

2. Jul 13, 2006

### neutrino

The p.d between A and B is $$-\int_{A}^{B}\vec{E}.d\vec{l}$$. In your problem this reduces to $$-\int_{0}^{3.97}E_xdx$$. Can you do it from here?

Last edited: Jul 13, 2006
3. Jul 13, 2006

### Andrew Mason

Perhaps you could show how you are doing the integration. I am not sure about your expression for $E_x$. Is the field $\vec{E} = 3.91\hat{x}$ N/C (ie. constant field of 3. 91 N/C in the x direction) or is it: $\vec{E} = 3.91x\hat{x}$ N/C (a linearly increasing field)?

AM

4. Jul 13, 2006

### rjnara

Thanks guys :)

5. Jul 14, 2006