Finding Electric Field at Point x Away from Origin

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Homework Help Overview

The discussion revolves around finding the electric field at a point located a distance x from the origin, considering the contributions from three charges. The subject area is electrostatics, specifically the calculation of electric fields using vector addition.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to apply the equation E = kq/r² and considers the vector addition of electric fields from multiple charges. They express uncertainty regarding the correct application of trigonometry and the Pythagorean theorem in their calculations.

Discussion Status

Some participants question the dimensional correctness of the original poster's expression for r and suggest using the Pythagorean theorem instead. Others acknowledge the symmetry of the problem, indicating that the vertical components of the electric field may cancel out, which simplifies the calculation.

Contextual Notes

There is a noted lack of understanding of the underlying concepts by the original poster, which may affect their ability to apply the equations correctly. The discussion includes a correction of a typo regarding the expression for r.

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How do I find the electric field at a point p distance x away from the origin?

I guess the y component cancels. I should use the equation E = kq/r2 and add the electric field made by the 3 charges as vectors, but how do I do that?

My attempt:

r = x/√(x2 + a2)

cosθ = x/r

Ex = 2kqx/√(x2 + a2)3/2 − kq/x2

Is this correct? I don't really understand the concepts well so if someone can explain that to me it'll be nice.
 
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r = x/√(x2 + a2) can't be right - the dimensions aren't right; right side has distance over distance. Just use the Pythagorean theorem to find the distance.

Find the horizontal part of E = kq/r^2 using trigonometry.
 
Oops, I made a typo on that. I meant to say that r = = √(x2 + a2)
 
Good show. Put in the trigonometry and you will be nearly finished.
Clever of you to notice that symmetry means you don't have to do the vertical part of the calculation.
 

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