Q- Four charges q₁ = q₃ = - q and q₂ = q₄ = + q, where q = 7 µC, are fixed at the corners of a square with sides a = 2.2 m, as in figure.

(a) Calculate the x- and y-components of the net electric field at the midpoint M of the bottom side of the square.

(b) Find the total force exerted on q₄ by the charges q₁, q₂, and q₃

q₁ ♦                      ♦  q₄

q₂ ♦                  ♦ q₃

Solution: