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)