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Re: emf, potential, voltage



I'm surprised no one (have I missed a post?), has mentioned the analogous
relation using MMF, reluctance, and flux to emf, etc.

bc

P.s. a resistor is not a resistor when it contains a diode.

brian whatcott wrote:

At 23:39 3/11/01 -0500, Carl Mungan wrote:
I would like to sharpen my understanding of the distinction between
potential difference, voltage, and emf.
/snip/
.. We define a source of emf as a device or element that supplies
electromagnetic potential energy to charges flowing through it. The
emf is the potential energy change per unit charge.

Two obvious examples are batteries and ac generators. Resistors
always dissipate energy and hence are not emf's....

In my view, the term emf is largely historical baggage.
There is a consensus about electrochemical cells, thermocouples,
photovoltaic devices, generators etc. as being active rather than
passive.

In fact, a resistor can be made to deliver an emf with the aid of a
germanium diode and a blow torch, but we much prefer to act as if it were
silent, electrically. The term is operationally relatively unhelpful.
There is no great burden of insight which it offers.

brian whatcott <inet@intellisys.net> Altus OK
Eureka!