Re: mag field of infinite wire (summary)

[Bob Sciamanda <trebor@VELOCITY.NET>]

I guess I withdraw this objection.  The B field is not a measureable, the
force on a charge is - this is the old parity conundrum - rooted in our
cross product convention.  Mea Culpa!

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor
----- Original Message -----
From: "Bob Sciamanda" <trebor@VELOCITY.NET>
To: <PHYS-L@lists.nau.edu>
Sent: Friday, March 29, 2002 5:43 PM
Subject: Re: mag field of infinite wire (summary)


> From: "Carl E. Mungan"
> > Solution #2 - adapted from a private email from Ben Crowell
> >
> > Consider a charged particle located along the y-axis and suppose it
> > is moving radially toward the wire. If there is a B_z, then the
> > particle experiences a nonzero force in the azimuthal direction. But
> > this is impossible by symmetry, since the wire is symmetric with
> > respect to reflection across the yz-plane.
>
> But there is a definable azimuthal direction - the direction of the wire's
> actual B field (circles in a preferred direction around the wire,
correlated
> to the current's direction along z).
> The above symmetry argument would forbid these circular B lines - which
> exist.
>
> Bob Sciamanda (W3NLV)
> Physics, Edinboro Univ of PA (em)
> trebor@velocity.net
> http://www.velocity.net/~trebor