🚀 go-pugleaf

David Thiessen wrote:

(initial paragraphs deleted)
>
> Chris, who seems to immediately see universal
>consequences of my statement, raised his hand and asked,
"If magnetic
>forces can do no work on moving charges, how can your big
horseshoe >magnet >pick up a steel plate like you showed
us?"  Of course, I had >never thought of such a question
and could not immediately answer him >and I did my usual
I'll have to think about that.
>
   I find it a bit easier to think in terms of a current
carrying wire in an external perpendicular magnetic field:
but the underlying problem
is still the same. If the B field does no work on the
moving electrons why then will the wire accelerate.

   That the wire as a whole accelerates is due to the
vector sum of the magnetic force on all the individual
moving electrons. Therefore, that the wire accelerates
presents no problem: there is no reason to assume that
it should behave as a single electron does.

   However, since the wire accelerates, it does accelerate
the moving electrons along with it. However, there are now
additional forces between the atoms in the wire and the
moving electrons. It is these internal forces which are
causing the electrons to accelerate. The magnetic field
is still doing no work on any one electron.

Ed Schweber
e-mail: EdSchweb@ix.netcom.com