Find the magniture of the net electrostatic force exerted on

Find the magniture of the net electrostatic force exerted on the point charge.

Four point-like charges are placed as shown in the figure, three of them are at the corners and one at the center of a square. 42.0 cm 011 each side. Find the magnitude of the net electrostatic force exerted 011 the point charge q_4. Let q_1 = q_3 = +23.0 mu C, q_2 = -33.0 mu C, and q_4 = -50.0 mu C.

Solution

Here ,

for the electric force on q4 due to q1 and q3

F1 = k * q4 * (q1 - q3)/(sqrt(2)*a/2)^2

F1 = 9 *10^9 * (-50 *10^-6) * (23 *10^-6 - 23 *10^-6)/(0.42/(sqrt(2)))^2

F1 = 0 N

for the electric field on q4 due to q2

F2 = k * q2 * q4/(a/sqrt(2))^2

F2 = 9 *10^9 * 33 *10^-6 * 50 *10^-6/(0.42/sqrt(2))^2

F2 = 168.4 N

the magnitude of net electrostatic force exerted on the point charge is 168.4 N