Five point charges, each of + q coulomb are situated at the vertices of a regular hexagon of side / metre Fig. The resultant force on charge - q placed at the centre ofthe hexagon will be

See fig. The different forces acting on (-q) charge are shown in the figure. It is obvious from the figure that forces F1 and F4; and F2 and F5 mutually cancel each other. Hence the net force is F3 which is given byF3=14πε0×q2l2