- #1

- 5

- 0

## Homework Statement

A square, with charges at each corner. The upper left (1) has a charge of +q. The upper right (2) has a charge of -2q. The bottom right (3) has a charge of +2q. The bottom left (4) has a charge of -q. The square has side length a.

a = 5.20 cm and q = 11.8 nC

Find the EF at the center of the square.

## Homework Equations

This was the equation that my prof gave us to deal with an observation point (in this case the center of the square) introduced into an Electric Field:

[tex]\vec{E}[/tex]([tex]\vec{r}[/tex] = [k (Q) ([tex]\vec{r}[/tex] - [tex]\vec{R}[/tex]] / [([tex]\vec{r}[/tex] - [tex]\vec{R}[/tex])^3]

Where r = the actual distance from the source charge to the observation point and R = the distance of the source charge from the origin.

## The Attempt at a Solution

I started by determining the distances between the source charges and the observation point, which all were a/[tex]\sqrt{2}[/tex], by pythagorean theorem.

I plugged this into the equation and got an answer of zero, which immediately flagged my attention, but I can't see why it came out that way. I then plugged the numbers into the equation for the second charge and got an answer of -1.57 x 10^14. This seemed very large, even though the charge of q is fairly large to begin with...

I left off there, maybe you guys could help me out and point out where I'm making my error...

Thanks,

-B