- #1
exitwound
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Homework Statement
Homework Equations
E=kQ/d^2
The Attempt at a Solution
If we choose a point P along the X-axis, with a distance X from the origin, we get this:
[tex]E_{P1}=\frac{kQ_1}{d^2}[/tex]
[tex]E_{P2}=\frac{kQ_2}{d^2}[/tex]
Assuming that Q=1 for simplicity:
[tex]E_{P1}=\frac{k(-7)}{(L+x)^2}[/tex]
and
[tex]E_{P2}=\frac{k(3)}{x^2}[/tex]
Basically, I've chosen P to be to the right of Q2, giving the distance between Q1 and P to be L+x and the distance between Q2 and P to be x.
If we want to find the point in space where the sums of the Electric fields is zero, we add up the field from Q1 and the field from Q2 and set equal to zero.
[tex]E_{P1}=\frac{k(-7)}{(L+x)^2} + \frac{k(3)}{x^2} = 0[/tex]
[tex]E_{P1}=\frac{k(-7)}{(L+x)^2} = - \frac{k(3)}{x^2}[/tex]
I end up with, after assuming L=1, cross-multiplying:
-7x^2 = (-3)(1+x)^2
But when I solve this, there is no real answer.
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