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## Homework Statement

Find the magnitude and direction of net electric field at the center of the square array of charges. Find [itex] E_x and E_y [/itex]

The square array of charges http://postimg.org/image/4gf94ymmf/

## The Attempt at a Solution

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My attempt at drawing in the force vectors http://postimg.org/image/mae0fm1d9/ . Now the +3q and +q's should contribute a net of zero to the electric field and they can be ignored. So, we have [itex] E = k [ -2q^2 / d^2 + q^2/d^2 + 5q^2/d^2] = 4k q^2/d^2[/itex]

Taking the x-component of the field we have

[itex] E_x = (4k q^2/d^2)cos(45)[/itex]

the y-component:

[itex] E_x = (4k q^2/d^2)sin(45)[/itex]

This isn't right or I would not be posting here... so what am I doing wrong? I'm really not understanding how to do these types of problems for net fields in squares. Have I even drawn the vectors correctly?