Charges +q and +q are fixed at points (a,0) and (0,a) respectively. A charge −2q is fixed at (0,0).
a. (i) State the quadrant in which the net electrostatic force on the charge at (0,0) lies.
b. (ii) If the charge at (0,0) is changed to +2q, state how the direction of the net force on this charge will change. Give a brief explanation.