A capacitor is constructed of two concentric conducting cylindrical shells. The radius of the inner cylindrical shell is 2.39 x 10^-3 m, and that of the outer shell is 2.46 x 10^-3 m. When the cylinders carry equal and opposite charges of magnitude 2.0 x 10^-10 C, the electric field between the plates has an average magnitude of 5.0 x 10⁴ V/m and is directed radially outward from the inner shell to the outer shell. Determine (a) the magnitude of the potential difference between the cylindrical shells and (b) the capacitance of this capacitor.