1. The problem statement, all variables and given/known data A particle is charge +e is incident on an electric dipole of charge +e and a charge of -e separated by a vector d (which runs from -e to +e). Use the Born approximation to calculate the differential scattering cross section as a function of the initial wave vector, the scatter wave vector, and the standard Rutherford scattering cross section. 2. Relevant equations 3. The attempt at a solution So they gave me the relative positions of the two charges. But I do not see how this is possible without knowing the absolute position of one of charges. Don't I need that in order to write down the potential?