1. For a point charge Q situated at the point (1, 2, 0), find the potential difference between the point A(3, 4, 1) and the point B(5, 5, 0).
2. For the arrangement of a linear electric dipole consisting of point charges Q and at the points (0, 0,d/2) and (0, 0,-d/2), respectively, obtain the expression for the electric potential and hence for the electric field intensity at distances from the dipole large compared to d.