Question

In the figure, eight particles form a square, with distance d between adjacent particles. -4g -2g +5 -5 -2q +4g -9 What is the electric potential at point P at the center of the square if the electric potential is zero at infinity? Use q, d and Click here to enter or edit your answer k 4

Answer 1

The charges +q, -4q, -q and +4q are at the four corners of a square having side 2d. Therefore, the distance of point P from these charges is the half of the diagonal.

Distance of point P from the aforesaid charges=

On the other hand, the distance of point P from the charges -2q, +5q, -2q and -5q is d (as point P lies at one corner of a square having side d).

Therefore, the potential at P is

V=   $\frac{-q}{2^{1/2}d} -\frac{2q}{d}-\frac{4q}{2^{1/2}d}+\frac{5q}{d}-\frac{q}{2^{1/2}d} -\frac{2q}{d}+\frac{4q}{2^{1/2}d}-\frac{5q}{d}$

= $-k\frac{4q}{d}$