A -3.0 nC charge is on the x-axis at x = -10 cm and a +4.0 nC charge is on the x-axis at x = 20 cm.

Question

At what point or points on the y-axis is the electric potential zero?

Answer 1

electric potential is the scalar addition of each component.

V= kq/r+ kq/r= -k3.0nC/(r+0.10)+k4nC/(r-0.20)

at V=0
3(r-.20)=4(r+.10)
r= -.6-.4= -1meter

check V(-1)=k(-3)/(-.9)+k4/(-1.2)=0