- #1

UselessLadder

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## Homework Statement

Hi,

I'm studying electric charges and fields, and I have a quick question about this example in my book:

Everything is straightforward except the subscripts (13 and 23) on

*r*in the denominators of initial Coulomb equations for F

_{1}and F

_{2}. In the next step they just plugged in the distances, so those numbers don't seem to do anything, and there are no subscripts in the original formula. So what are they?

## Homework Equations

F = k [(q

_{1}q

_{2})/r

^{2}]