Talk:Nernst–Planck equation

What is phi?

This article doesn't say anywhere. —Preceding unsigned comment added by 24.13.162.248 (talk) 05:17, 5 October 2010 (UTC)

It's the electric potential; the first equation defines the electric field as $E=-\nabla \phi -{\frac {\partial \mathbf {A} }{\partial t}}$ where, according to "standard usage" $\phi$ is the electric potential and $\mathbf {A}$ is the magnetic (vector) potential --Osquar F (talk) 08:12, 15 August 2012 (UTC)