Re: [Phys-l] Force on a charged particle from a magnetic field

["Fayngold, Moses" <fayngold@ADM.NJIT.EDU>]

> But there is time varying flux in the frame of the proton.  The only
> way to avoid that involves using an infinitely large magnet.

> That's why I carefully defined the magnetic field to be uniform, so there is
> no change in flux with time (classically). Specifically, how do you get the
> time varying flux that ultimately produces an electric field to move the
> proton? (Again, without an appeal to relativity.)

                             ********
 You do not need a time varying magnetic flux around the proton in the 
co-moving RFin order to get an electric force on it. The electric field 
will appear even in the region of a HOMOGENEOUS magnetic field 
(e.g. within sufficiently large and tightly wound solenoid) if you are moving, 
say, perpendicular to its axis. And there is a specific mechanism for it - 
the emergence of the opposite electric charges on the solenoid's sides making 
aqute or zero angle with the direction of your motion. This is purely 
relativistic effect, providing specific illustration of Bob Sciamanda's point. 
In this respect I also agree with John Denker, that while the Maxwell's 
equations are totally consistent with Relativity, this by itself does not 
guarantee that everything can be explained plainly within Maxwell's theory
alone. Here we must explicitly apply the Lorentz transformation to see the 
appearance of the charges on the solenoid's wires that are electrically
neutral in the solenoid's rest frame. So I think that the emergence of the
electric field around the proton in a co-moving RF in given situation cannot
be explained without explicit reference to Relativity.

Moses Fayngold,
NJIT