Point charge 3.5 μc is located at x = 0, y = 0.30 m, point charge -3.5 μc is located at x = 0 y = -0.30 m. what are (a)the magnitude and (b)direction of the total electric force that these charges exert on a third point charge q = 4.0 μc at x = 0.40 m, y = 0?

Hi, thank you for posting your question here at .

To solve this problem, we use Coulomb's Law:

F = kQ1Q2/d^2, where k = 9x10^9

Q1 = 3.5 uC
Q2 = -3.5 uC
Q3 = 4.0 uC

But first, we find the distance between Q1 and Q3 and between Q2 and Q3.

d between Q1 and Q2:
d = sqrt[(0-0.4)^2+(0.3-0)^2]
d = 0.5 m

d between Q1 and Q3:
d = sqrt[(0-0.4)^2+(-0.3-0)^2]
d = 0.5 m

Through force balance, F between Q2 and Q3 - F between Q1 and Q3:



Thus, the net force is -1 x 10^-12 C