The arrangement shown consists of three elements. (i) A thin rod of charge −3.0 μC that forms a full circle of radius 6.0 cm. (ii) A second thin rod of charge 2.0 μC that forms a circular are of radius 4.0cm and concentric with the full circle, subtending an angle of 90∘ at the centre of the full circle. (iii) an electric dipole with a dipole moment that is perpendicular to a radial line and has magnitude 1.28×10^−21 C/m . Find the net electric potential in volts at the centre.