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Homework Statement
Consider an electric dipole in the attached document. At point P, the fields E_{+} due to q+ and E_{} due to q are:
E_{+} = kq/(ra)^{2}, E_{} = kq/(r+a)^{2}
Then total field at P is:
E = E_{+} + E_{} = kq [ 1/(ra)^{2}  1/(r+a)^{2}] yhat
Homework Equations
See question 1.
The Attempt at a Solution
So this post is just trying to comprehend the example problem above. I don't believe I'm fully understanding electric field. In the problem above, they have a point P without a charge given. They say that the impact of the electric field of +q occurs at a distance of ra which makes sense if P is a postive charge. But then for q, it takes place at a distance of r+a. What I don't understand for this, shouldn't it take place at a distance of 2a+r? It seems like it'd be a distance of 2a from Point P. Or are we considering that the electric field is moving towards q? I'm not sure I understand this problem...
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