(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Is there a way to nicely compute the force between two configurations of point charges ?

Here is an example. Two "squares" of charges (each separated by a rigid insulator of length a) are separated by a distance d, measured with respect to their centers. Instead of taking a sum over 2^4 = 16 terms, is it possible to "summarize" each square with something like an overall charge or an overall electric field?

[tex]

\begin{verbatim}

e+ --a-- e-

| |

a a

| |

e+ --a-- e-

\end{verbatim}

[/tex]

2. Relevant equations

3. The attempt at a solution

Finding an "effective charge" for each square doesn't seem right (since the total charge is zero). Also, I can't find a way to get out of doing lots of algebra by using the electric field produced by one square and calculating the force on the other square from that, although it would seem that the vertical component of the field cancels along a line joining the centers. Is this right?

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# Homework Help: Electrostatics: force calculation

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