Two charges q1= +3x10^-6 and q2 = -6x10^-6 C are placed along the x axis at orgin and 1.2m respectively,
a) At what distance relative to the charge q1 along the line through the charges is the net electric potential zero?
b) What would be the electric potential energy of a third charge of q= +12 x 10^-6
C placed at this point found in the part (a) of this problem?