Two conducting spheres with diameters of 0.54 m and 1 m are separated by a distance that is large compared to the diameters. The spheres are connected by a thin wire and are charged to 6.4 C . What is the potential of the system of spheres when the reference potential is taken to be 0 at ? The permittivity of a vacuum is 8.8542 10^12 C^2 /N m^2 . Answer in units of kV.