Calculating Electric Field Components for Discrete Charge Distribution

AI Thread Summary
The discussion focuses on calculating the electric field components at the origin due to two test charges, q1 and q2, with specific coordinates and magnitudes. The user attempts to compute the electric field using the formula E=Kq/r^2 but struggles with the direction of the electric fields generated by the charges. It is emphasized that the electric field from a negative charge points towards it, while that from a positive charge points away. The user expresses confusion about the directions and their implications for the calculations, indicating a need for clarity on how to apply these principles correctly. The conversation highlights the importance of understanding charge interactions in electric field calculations.
clb399
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Homework Statement


Two test charges are located in the x–y plane. If q1 = -3.50 nC and is located at x = 0.00 m, y = 0.680 m and the second test charge has magnitude of q2 = 3.60 nC and is located at x = 1.00 m, y = 0.650 m, calculate the x and y components, Ex and Ey, of the electric field, , in component form at the origin, (0,0). The Coulomb Force constant is 1/(4π ε0) = 8.99 × 109 N·m2/C2.

Homework Equations


E=Kq/r^2

The Attempt at a Solution


So first I converted all of the given data.
q1= -3.5x10^-9 C
q2= 3.6x10^-9 C
r1=.680
r2=sqrt(1.1926)
angle=33degrees using tan^-1(.650/1)

Then I solved for E1y since it is entirely in the y direction:
E1y= K(-3.5x10^-9)/(.680)^2= -68.05

Then solved the x and y components of E2
E2x= K(3.6x10^-9)/(1.1926)^2(cos(33)) = 22.76
E2y= K(3.6x10^-9)/(1.1926)^2(sin(33))= 14.78

Then:
E1y+E2y
E2x
This is my newest answer that I've come up with but all of them have been wrong. I'm not sure what I'm missing or what's going wrong.
 
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The electric field should be pointing the same direction as the force on a positive test charge. You can use this as a consistency check.

Is something else than the direction wrong? It would help us spot your error if you provided the answer from the solutions manual.
 
I do not have a solutions manual, this is an online assignment. And what direction is wrong?
 
clb399 said:
I do not have a solutions manual, this is an online assignment. And what direction is wrong?

Both, the field of a negative charge should be pointing towards it and that of a positive away from it as a negative charge would attract and a positive repulse a positive test charge.
 
What would the directions change? I have no idea how that helps me in the problem. I understand what you're saying, I just don't see how it applies.
 
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