Here is my problem: A charge of -q is located at x=a. Another charge, +q, is at x=2a. This sequence of alternating charges continues indefinitely in the +x direction. What is the electric field at the origin?(adsbygoogle = window.adsbygoogle || []).push({});

So I figure I need an infinite alternating sum. The equation to be used is [tex] \frac{q}{4\pi\epsilon_0r^2} [/tex] So the sum would be [tex] \sum \frac{(-1)^nq}{4\pi\epsilon_0(na)^2} [/tex]. Which can be factored to [tex] \frac{q}{4\pi\epsilon_0a^2} \sum \frac{(-1)^n}{n^2} [/tex]. (sum from n=one to n=infinity)

Is that correct so far? Im not sure how to do the sum..... Any help please, Thx!

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# Electric field from infinite charges

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