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## Homework Statement

This question is actually the simplification of a more complicated one. A particle of charge +q is placed at a point A while another particle of charge +2q is placed at B, a distance of 2r to the right of A. The midpoint between the distance is denoted as O. What is the electric field intensity at O ?

## Homework Equations

E=F/q

## The Attempt at a Solution

Honestly, if particle A has a charge of +q and if B has a charge of +q, then the electric field at O ought to be zero as they cancel each other out. But I can't understand it mathematically. Suppose I consider the electric field at point O due to the particle at A, then it's electric field E(A)=(kq)/(r^2) and the electric field at point O due to particle B E(B)=(k2q)/(r^2) where k=(1/4∏ε0) Hence the total electric field E(T)=E(A)+E(B)=(3kq)/(r^2) ??? Isn't it supposedly zero ? One might say that I ought to subtract them, but my textbook says that the electric field due to multiple charges is the

**vector sum**

**of the individual electric fields. (Like the principle of superposition). Please advise on my mistake. Thank you.**