A -4.50 nC point charge is surrounded by a electrostatic conducting spherical shell that has an inner radius of 7.00 cm, an outer radius of 9.00 cm, and a net charge of +6.50 nC.
a) Calculate the electric potential 8.00 cm from the point charge. (200V) (Remember that if E=0, dV/dr = 0)!
b) Calculate the electric potential 4.00 cm from the point charge. (-233 V)
c) How much energy would a proton require to travel from infinitely far away to the inner shell surface? (3.20x10-17 J).