Re: mag. force on wire?

[Bob Sciamanda <trebor@VELOCITY.NET>]

Leon wondered:
> Just how is it that the force on moving charges
> "contained" in a wire is transferred to the wire
> itself? I've problems with the two explanations that
> seem pretty standard. That is, by collisions (with
> what, exactly, and what happens at the boundary?); and
> by electrostatic separation of charges (what happens
> if both positive and negative charges are equally
> responsible for charge flow?)

I am not familiar with the "electrostatic separation" explanation; but the
"collisions with the ion lattice" idea is a useful model.

F=QVxB will produce the same direction of force for a given current
direction, however that current is divided among positive vs negative
carriers (both Q and V change sign)  That's why the force on a conductor
can be evaluated in terms only of the current  (dF = I dLxB, where dL is a
vector in the direction of the current) - with no regard to the sign(s) of
the carriers.

At the air/conductor boundary, any carriers forced off the surface will be
called back and will call the conductor body toward them (by N3) because
of  their "image charge" in the conductor.

Hope this may be helpful - don't hesitate to prod further.

Bob

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor