Re: force on an asymmetrical conductor

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"Lord Snooty" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
>
> > I repeat- I did not assume or imply grad(B) not equal to 0.  When I
> > originally answered, I did not even think of grad(B). All I intended to
say
> > is that force =Bli is a simplification of the Lorentz force equation and
is
> > not always applicable in a simplified manner.
> > However, you have, in fact, made another assumption and this may be the
> > killer. You have assumed that adding the magnetic coating does not
change H
> > but does increase B. Why? Is this reasonable in light of the applicable
> > Maxwell's equations (consider  integral form ignoring any time dependent
> > terms-it may be easier to see that way).
> > --
> > Don Kelly
> > [EMAIL PROTECTED]
>
> 1. What's incorrect about B*I*L in this context?
---------
Normally where Bli is used it applies to a current carrying condictor in
which the loop is closed in a region far from the field. Then there is only
the one active conductor. It can be applied to a coil in a rotaty case as in
a meter movement. Again, going back to conservation of energy- there is no
change in energy with position. However, see below.
> 2. You may be right about the coating. Stuff it back in the box in that
case.

You also mentioned a shield- that initially sounds more attractive. However,
a magnetic field is conservative. It can be used to do work but you  must
pay back the energy. It is not a source of energy in spite of claims of the
perpetual motion crowd. It simply facilitates the transfer of energy from
electrical to mechanical. Now consider the superconducting coil which
effectively has 0 resistance and 0 voltage required to circulate the
current. As soon as the conductor moves there will be a non-zero speed
voltage Blv induced in this coil, no matter how small. This voltage opposes
the flow of current This means that non 0 energy is taken from the coil but
there is no energy source in the superconducting coil. The current will then
drop to 0 so then you will have a case of no current, no force, and no
motion. The reason a real motor works is that there is a voltage applied
which is larger than this speed voltage and a power transfer from electrical
to mechanical systems takes place. If the speed voltage exceeds the applied
voltage power transfer is from mechanical to electrical.
>
You are faced with the perversity of inanimate objects.

Don Kelly
[EMAIL PROTECTED]
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