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



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