1) The charges and coordinates of two charged particles held fixed in the xy plane are q=+3.0 C, XA = 3.5 cm, yA = 0.5 cm, and qB = -4.0 C, XB = -2.0 cm, yB = 1.5 cm. Where could you locate a third charge qc+ 4.0 C such that the net electrostatic force on QB is zero? 2) A molecule may be modeled approximately as a positive charge q at x = a and a negative charge -q at x=-a. Evaluate the electric field on the y-axis, and find an approximate expression that is valid at large distance (y>>a).