$q_{A}=0$ and the spheres at B and C carry the same charge $q_{B}=q_{C}=q.$ It is known that the sphere B exerts an electrostatic force on C which has a magnitude $F=4~\mbox{N}.$ Suppose an engineer connects a very thin conducting wire between spheres A and B. Then she removes the wire and connects it between spheres A and C. After these operations, what is the magnitude of the force of interaction **in Newtons** between B and C?