Re: mag field of infinite wire (summary)

[Bob Sciamanda <trebor@VELOCITY.NET>]

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