Spherical Multipole Moments High Quality Content by WIKIPEDIA articles Spherical multipole moments are the coefficients in a series expansion of a potential that varies inversely with the distance R to a source, i.e., as 1/R. Examples of such potentials are the electric potential, the magnetic potential and the gravitational potential. For clarity, we illustrate the expansion for a point charge, then generalize to an arbitrary charge density rho. hrough this article, the primed coordinates such as mathbf{r{prime}} refer to the position of charge(s), whereas the unprimed coordinates such as mathbf{r} refer to the point at which the potential is being observed. We also use spherical coordinates throughout, e.g., the vector mathbf{r{prime}} has coordinates ( r{prime}, theta{prime}, phi{prime}) where r{prime} is the radius, theta{prime} is the colatitude and phi{prime} is the azimuthal angle.
