Electric field and potential at the centre of a square with four charges

[JR9]

Homework Statement

4 charges of +5µC, +3µC, -4µC and +2µC form the 4 points of a square of side length 2m. Calculate the field strength and potential at the centre of the square.

Homework Equations

F=1/4π[PLAIN]http://upload.wikimedia.org/math/d/3/c/d3c305fc416b971cd6d284564e51bf85.png[SUB]0[/SUB] X Q1Q2/r²
E= Q/4π[PLAIN]http://upload.wikimedia.org/math/d/3/c/d3c305fc416b971cd6d284564e51bf85.png[SUB]0[/SUB] r²

The Attempt at a Solution

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[berkeman]

Homework Statement

4 charges of +5µC, +3µC, -4µC and +2µC form the 4 points of a square of side length 2m. Calculate the field strength and potential at the centre of the square.

Homework Equations

F=1/4π[PLAIN]http://upload.wikimedia.org/math/d/3/c/d3c305fc416b971cd6d284564e51bf85.png[SUB]0[/SUB] X Q1Q2/r²
E= Q/4π[PLAIN]http://upload.wikimedia.org/math/d/3/c/d3c305fc416b971cd6d284564e51bf85.png[SUB]0[/SUB] r²

The Attempt at a Solution

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Welcome to the PF. Keep going! Use those equations and draw a figure... :-)