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Re: point particles



For those interested in the "search for the electric
dipole moment of the electron" see the website
www.amherst.edu/~physics/hunter.html and download the
research article on the subject and there are other
references in the article.
Regards,
Richard Lindgren

On Thu, 22 Jan 2004 13:15:16 -0500
Bob Sciamanda <trebor@VELOCITY.NET> wrote:
Ludwik,
I don't know who made that claim, but the dipole moment
of a non neutral
charge distribution is defined only relative to an
origin. Perhaps an
assumed origin was embedded in the context of the
discussion(?).
.
P.S.: J Denker's specification of the CM as the assumed
origin for the
"physics" dipole moment is news to me. In my experience
no mention of the
CM occurs in any textbook definition of the physics
electrical dipole
moment. John, would you give a reference for this
distinction between a
"mathematical" vs "physics" dipole moment?

Bob Sciamanda
Physics, Edinboro Univ of PA (Em)
http://www.velocity.net/~trebor/
trebor@velocity.net
----- Original Message -----
From: "Ludwik Kowalski" <kowalskil@MAIL.MONTCLAIR.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Thursday, January 22, 2004 1:00 PM
Subject: Re: point particles


Yes, but the claim was made that the
dipole moment of a point charge (NOT
Q=0) is an intrinsic property of the object
in which that point charge is located. By
"intrinsic" I mean "not dependent of the
location of the reference point. How this
can such claim be justified?
Ludwik Kowalski



On Thursday, January 22, 2004, at 12:18 PM, Bob
Sciamanda wrote:

> Huh? The center of mass location has nothing to do
with the electrical
> dipole moment, the dipole moment is calculable from
only a knowledge
> of
> the charge distribution.
>
> In answer to another, related query, the dipole moment
of a charge
> distribution is in general dependent upon one's choice
of origin for
> the
> calculation. But if the monopole moment is zero
(overall electrical
> neutrality) the dipole moment is independent of the
choice of origin.
>
> Bob Sciamanda
> Physics, Edinboro Univ of PA (Em)
> http://www.velocity.net/~trebor/
> trebor@velocity.net
> ----- Original Message -----
> From: "Richard A. Lindgren" <ral5q@VIRGINIA.EDU>
> To: <PHYS-L@lists.nau.edu>
> Sent: Wednesday, January 21, 2004 3:44 PM
> Subject: Re: point particles
>
>
>> . . .
>> If the electron had a slight displacement of its
center of
>> mass to its center of charge, it would have what is
called
>> an electric dipole moment. . . .