# Coulomb interaction not affected by presence of other charges

1. ### rajeshmarndi

251
One of the observation noted in connection with coulomb interaction is that, it is not affected by the presence of other charges. Why?

Thanks.

2. ### e.bar.goum

800
Could you possibly tell us where you read that? It doesn't sound quite right, but perhaps I misunderstand you.

From the law of superposition, we can write the effect of a set of N point charges q on a charge as

$F(r) = \frac{q}{4 \pi \epsilon_0}\sum_{i=1}^N \widehat{R}_i /|R_i|^2$

Where

$\widehat{R}_i$

is a unit vector in the direction of

$R_{i} = r - r_{i}$.

Is this perhaps what you meant? This is just due to the linearity of the electrostatic interaction - any linear system may be decomposed into a linear superposition, wikipedia has an ok writeup.

3. ### rajeshmarndi

251
I read it on the twelve standard book of my state board.

Also I found the same on this site.

Following observations can be noted in connection with Coulomb’s interaction:

(a)...
(b)..
(c)Coulombs interaction is not affected by the presence of other charges in the neighborhood.

What exactly does it say?

4. ### e.bar.goum

800
I find that statement vauge too, but I would interpret it as I stated above - that the law of superposition holds.

I agree.

6. ### rajeshmarndi

251
Can you explain what does linearity of the electrostatic intersection, exactly mean.

What I understand from superposition principle, is that all the charges when placed near each other behave independently of each other and just only their vector sum add up. May be this is what the statement mean.

And thanks for the reply.

7. ### e.bar.goum

800
Sorry, what I mean by "the linearity of the electrostatic interaction" is just that because the coloumb/electrostatic interaction is linear, you can therefore apply the superposition principle, as you described above.