Q.3 Three point charges are placed at the following points on x-axis: 3µC at x=0, -4µC at x=50cm and

Question

-5µC at x=120cm. Calculate the force on -4µC charge.

Answer 1

At 50 the force on Q2 is to the left (attractive) from Q1 and to the left (repulsive) from Q3 so they add and are in the -x direction.
F = -k * 4µC [ 3µC/0.50^2 + 5µC/0.70^2 ]