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Re: Faraday induction



Eugene Mosca wrote:

How about energy per unit charge?

Does this mean that the kinetic energy per unit charge of charged particle
in an beam passing through a surface is voltage?

No, that's not what I had in mind.

Loosely speaking, I was thinking of the energy-per-unit-charge of an
idealized test particle that had no kinetic energy, no gravitational
potential energy, et cetera.

More precisely, I was thinking of the part of the energy due solely to
the interaction of the particle's charge with the applied field. This
could be ascertained by comparing the energy of the charged particle
with the energy of an otherwise-similar uncharged particle.

In the example given of the cut conducting ring in an increasing magnetic
field, inside the material of the conductor the tangential (azimuthal
component of the net electric field is everywhere zero. Thus, for a path
staying within the conductor from one side of the cut to the other the
voltage difference is zero. Correct?

Yes. (In the limit of a good conductor, to an excellent approximation,
blah, blah, blah.)


Does the voltage of a battery differ from the
terminal potential difference?

It does not differ in ordinary situations, such as situations where
Kirchhoff's laws apply.

The terminal potential difference ?V is equal to the emf - Ir, where r is
the internal difference and I is the current. The voltage between the
terminals is also equal to the emf ­ Ir, but we cannot write this without
using the term emf, or can we? How is this relation expressed without using
the emf word?

An electronics engineer would state it as follows:
(terminal voltage) = (open-circuit voltage) minus (I) times (R)
(under load) (Thevenin equivalent)

This is discussed at e.g. pages 10 and 11 of
http://www.ppi2pass.com/corner/fe-manual/dircur.pdf