Hello,
> > Why U for voltage/electromotive force?
> >
>
> In France, V is used for the potential itself. Potential differences are
marked
> by U, so that we don't mistake potential (defined relative to an arbitrary
> constant) to electromotive force (defined absolutely). The difference is
> little, but believe me, it helps quite a lot to prevent simple mistakes.
It's
> also quite useful when talking about motion driven by electric forces,
since v
> is then taken for velocities :)) .
We use the Greek phi for potential, then we introduce delta phi, which is
then renamed U (or V, according to people's predilections :-))
--Pavel