Re: The sign of work

[Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>]

In trying to justify the negative sign in dV=-E*ds, where
E and ds are the electric field and the displacement, I will
emphasize the dot product nature of E*ds. The potential
energy (per unit charge) increases when the dot product
is negative (obtuse angle between E and ds), otherwise
it decreases, or remains the same. The "uphill" is locally
defined by the direction of E; it has nothing to do with
the orientation of the x,y,z axes (with respect to local E).
There is no ambiguity here, as long as we agree that the
probe charge is positive. Right?
Ludwik Kowalski

> Daniel Schroeder wrote:
>
> > ... Now on to the main point.  It's certainly true, in this
> > situation, that work is done by the system and therefore
> > W>0 according to the "engineering" convention but W<0
> > according to the chemistry convention.  ...