# Electric field at the origin

"Three charges, +2.5 microC, -4.8microC, and -6.3microC, are located at (-0.20m, 0.15m), (0.50m, -0.35m), and (-0.42m, -0.32m) respectively. What is the electric field at the origin?"
Using the coordinates, I found that r12 = 0.0625 m2, r22 = 0.3725m2, and r32 = 0.2788m2. I then plugged that into the equation E = (kq)/r2, where k = 9 * 10^9.

Using that I found:
E1 = 3.6 * 10^5 N/C at 37º below the +x-axis.
E2 = 1.2 * 10^5 N/C at 35º above the -x-axis.
E3 = 2.0 * 10^5 N/C at 37º below the -x-axis.
Then the final components of the total Electric Field is:
Ex = 2.9 * 10^4 N/C
Ey = -2.7 * 10^5 N/C

However, the answer is 2.2 * 10^5 N/C for x, and -4.1 * 10^5 N/C for y. What am I doing wrong?

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siddharth
Homework Helper
Gold Member
You problem solving approach looks correct.

Maybe you went wrong in the arithemtic (+/- signs)? Or perphaps you've not calculated the angles correctly?

siddharth said:
You problem solving approach looks correct.

Maybe you went wrong in the arithemtic (+/- signs)? Or perphaps you've not calculated the angles correctly?
It was the angles.
E2 should be = 1.2 * 10^5 N/C at 35º below the +x-axis.