# Linear Charge Distribution Question

1. Jan 25, 2010

### im.zaur

1. The problem statement, all variables and given/known data
Find the electric field a distance z above the midpoint of a straight line segment of length 2L, which carries a uniform line charge $$\lambda$$.

2. Relevant equations
dE = 2 * (1 / 4$$\pi\epsilon$$) * ($$\lambda$$dx / r2) * cos$$\theta$$ $$\hat{z}$$

cos$$\theta$$ = z/r

r = $$\sqrt{x2 + z2}$$

3. The attempt at a solution
This an example question from my textbook with a full solution. The problem im having is that I don't understand where the x2 disappears right after this step.

E = 1 / (4$$\pi$$$$\epsilon$$ $$\int$$ (2$$\lambda$$z) / ($$\sqrt[3]{x2 + z2}$$) dx

And im not sure why the superscripts didn't work inside the square root function. Any help would be appreciated if anyone understands what im asking for.

Thanks

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