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Re: emf and batteries



on 22/3/04 11:29 AM, Ronald Newburgh at rgnew@BELLATLANTIC.NET wrote:

The term emf is an historical fly in amber. Until the early 19th
century the terms force and energy were often interchanged. The Latin
for force is "vis" and the Latin for kinetic energy is "vis viva" or
living force. The
term emf referred to energy, or more specifically an intensive energy -
electrical potential energy per unit charge.


It's more like the second half of the 19th Century, that any distinction was
made. The details that follow owe much to Martin Bailyn's book A Survey of
Thermodynamics AIP Press, 1994..

The word energy comes form the Latin energia and the Greek energeia, with
meanings of agency, force

I'm fairly sure the use of the term and concept of vis viva predates
"kinetic energy".

Joule spoke and wrote about vis viva (or living force) as contrasted with
Leibnitz's vis potentia or vis mortua. (or attraction in space). He did
not use the terms kinetic energy or potential energy. Joule asserted that
when heat (sic) is added to a body it can become internal living force
and/or internal attraction in space .

Helmholtz used the German word kraft sometimes to mean force and sometimes
to mean what we call energy.

Clausius also worked in this field but the first use of the terms potential
(or latent) and actual (or sensible) "energy" came with Rankine. He
introduced the term "potential energy" and the phrase "conservation of
energy".

Kelvin in Kelvin and Tait's Treatise on Natural Philosophy formalised the
use of the terms Kinetic Energy and Potential Energy as we know them. The
year was 1867

Brian McInnes


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