Re: non-potential voltages vs. Kirchhoff's laws

[John Denker <jsd@MONMOUTH.COM>]

At 04:28 PM 4/14/99 -0500, JACK L. URETSKY wrote:
> Dear jsd-
>        Are you saying that the gradient of an induced voltage is not
> an electric field?
> *************************************************************
> The term "potential difference" is acceptable when talking about DC
> circuits and capacitors, but when talking about induced voltages it is
> crucial to keep in mind that the induced voltage is *not* a potential!
> ****************************

1) If you tell me the voltage as a function of position, then we can take
the gradient and call that the electric field.  It will be a curl-free
electric field.

2) The Maxwell equations tell us that in the presence of a changing
magnetic field, you *cannot* tell me the voltage as a function of position.
 The voltage drop from point A to point B depends on the path taken from A
to B.  There will be some voltage difference, but the voltage will not be a
potential.

3) If you can't tell me the voltage as a function of position, it is not
possible to take the gradient thereof.  The question of whether this
non-existent gradient should be called an electric field is moot.

jsd