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Equal charges q are placed at x=0,2,4,8 m on x axis . Find the $\;|force|\;$ experienced by the charge at x=2 m

$(a)\;\large\frac{kq^2}{4}\qquad(b)\;\large\frac{kq^2}{9}\qquad(c)\;\large\frac{kq^2}{36}\qquad(d)\;zero$

Can you answer this question?

Answer : (c) $\;\large\frac{kq^2}{36}$
Explanation :
$\;Force \;on\;q_{2}=F_{q_{1}}+F_{q_{3}}+F_{q_{4}}$
$F_{net}=\large\frac{kq_{1}q_{2}}{2^2} \hat{i}-\large\frac{kq_{2}q_{3}}{2^2} \hat{i}+\large\frac{kq_{2}q_{4}}{2^2} \hat{(-i)}$
$q_{1}=q_{2}=q_{3}=q_{4}=q$
$F_{net}=-\large\frac{kq^2}{36} \hat{i}\;.$
answered Jan 29, 2014 by
edited Feb 13, 2014 by yamini.v