Transferring electric charge

From Coulomb's Law we have that, initially, the force between spheres B and C is given by $F_{BC}=k \frac{q^{2}}{l^{2}}$ where $l$ is the side of the triangle. Right after spheres A and B are connected, charge flows from B to A. Electrostatic equilibrium is reached when the electric potentials at points A and B are equal, which implies $q_{A}=q_{B}$ . Moreover, due to conservation of electric charge, we have that $q_{A}=q_{B}=\frac{q}{2}$ . Now the net charge of system AC is $\frac{3}{2}q$ . When A and C are connected their charges redistribute so that after equilibrium $q_{A}=q_{C}=\frac{3}{4}q$ . Therefore, the final force between B and C can be written as $F^{'}_{BC}=k \frac{(q/2) (3q/4)}{l^{2}}=\frac{3}{8}F_{BC}.$ Thus, we find that $F^{'}_{BC}=1.5~\mbox{N}$ .