Two charges q = +4.8 μC are fixed a distance d = 6.2 cm apart (see the figure). (a) With V = 0 at infinity, what is the electric potential at point C ? (b) You bring a third charge q = +4.8 μC from infinity to C. How much work must you do? (c) What is the potential energy U of the three-charge configuration when the third charge is in place?