  Although the expressions for energy densities involving electric and magnetic
fields are exactly analogous, the connections to forces and electromagnetic
potentials are vastly different. For electrostatic situations, the changes in
the \textit{electric} energy can be related directly to \textit{electric}
forces and to the electrostatic potential. The situation involving magnetic
forces and energy changes involves two fundamentally different situations. For
charged particles moving with constant velocities, the changes in both electric
and magnetic field energies are provided by the external forces that keep the
particles' velocities constant; there are no Faraday acceleration electric
fields in this situation. However, for particles that change speed, the changes
in \textit{magnetic} energy density are related to acceleration-dependent
Faraday \textit{electric} fields. Current undergraduate and graduate textbooks
deal only with highly symmetric situations where the Faraday electric fields
are easily calculated from the time-changing magnetic flux. However, in
situations that lack high symmetry, such as the magnetic Aharonov-Bohm
situation, the back (Faraday) acceleration electric fields of point charges
seem unfamiliar. In this article, we present a simple unsymmetric example and
analyze it using the Darwin Lagrangian. In \textit{all} cases involving
changing velocities of the current carriers, it is the work done by the back
(Faraday) acceleration \textit{electric} fields that balances the
\textit{magnetic} energy changes.
