A10.0 nc point charge and a 20.0 nc point charge are 15.0 cm apart on the x axis. a) what is the electric potential at the point on the x axis where the electric field is zero? b) what is the magnitude of the electric field at the point on the x-axis, between the charges, where the electric potential is zero? c) what is the direction of the electric field at the point on the x-axis, between the charges, where the electric potential is zero?