Two point charges lie along the y axis. A charge of q1 = -12.0 µC is at y = 6.0 m, and a charge of q2 = -5.0 µC is at y = -3.0 m. Locate the point (other than infinity) at which the total electric field is zero.

Answer 1

some point (0,y) on y axis between
y = -3 and y = +6

field up = k(-12)/(6-y)^2
field down = k(-5)/(y-3)^2
so
12(y-3)^2 = 5(6-y)^2

Answer 2

P=7