# Homework Help: Electric Fields components help

1. Sep 7, 2008

### lilangel50us

In a rectangular coordinate system, a positive point charge q = 9.00 nC is placed at the point x= 0.250 m, y = 0, and an identical point charge is placed at x= -0.250 m, y = 0. Find the x and y components and the magnitude and direction of the electric field at the following points.

(a) Find the x and y components and the magnitude of the electric field at the origin.

Since the two point charges are from equal distances from the origin, I got that as E_x =0, E_y=0, and E_net = 0.

(b) Find the x and y components and the magnitude and direction of the electric field at x= 0.500 m, y=0

I figured out that the angle of this would be 0 degrees from the positive x axis.

2. Sep 7, 2008

### lilangel50us

I realized I never finished typing out everything.

(a) I found that out conceptually. Since the two charges are positive, their electric fields will repel, and since they are equidistant from the origin, the origin will have no electric field.

(b) I'm not really sure what to do here.

I figure that E_y = 0. To calculate E_x, I think I would have to do the following:

E_x = (k(9.00 nC)/(.25)^2)/9.00nC = E_net

Am I doing it properly?

3. Sep 7, 2008

### Defennder

(a) looks ok by symmetry.

(b) You have to add up the E_x contributions for both charges. The one you wrote is for the charge at x=0.25 What about the one at x=-0.25?