Answer:
Electron must be placed at a distance of 2.69 ×10^5 m in the direction of positive y-axis.
Explanation:
Charge on electron = e = -1.6 × 10^-19 C
Mass of electron = m = 9.1 × 10^-31 kg
Charge at origin = q = -0.45 nC
According to given condition in the question:
Fe = Fg
kq1q2/r^2 = mg
(9 × 10^9)( -1.6 × 10^-19)( -0.45n)/r^2 = (9.1 × 10^-31)(9.8)
r = √7.2 ×10^10
r = 2.69 ×10^5 m in the positive y-axis direction