Re: point particles

[Ludwik Kowalski <kowalskil@MAIL.MONTCLAIR.EDU>]

On Wednesday, Jan 21, 2004, at 17:00 America/New_York, Dan Crowe wrote:

> A multipole expansion can be calculated for any charge
> distribution, including a single point charge.  The
> multipole expansion is calculated relative to a particular
> coordinate system.  If a point charge is not at the origin,
> the dipole moment, relative to the coordinate system, is
> nonzero.  See, for example, Eyges or Jackson.

Are you saying that the magnitude of the dipole
moment of a "system" can have any value,
depending on where the origin of our coordinate
system is? I was under the impression that the
dipole moment is a system property, like its total
mass or charge. Is this wrong?
Ludwik Kowalski