An electrostatic "dipole" is formed by placing a positive charge of q [C] on the z axis at z = d/2 and a negative charge of -q [C] on the z axis at z = -d/2. Determine the potential Φ(x, y, z) (with respect to infinity) at a point (x, y, z). Note: Determining the potential at a point "with respect to infinity" is equivalent to determining the potential at the point when the reference point is at infinity and the potential there is zero.