  We calculate the net change in generalized entropy occurring when one carries
out the gedanken experiment in which a box initially containing energy $E$,
entropy $S$ and charge $Q$ is lowered adiabatically toward a
Reissner-Nordstr\"{o}m black hole and then dropped in. This is an extension of
the work of Unruh-Wald to a charged system (the contents of the box possesses a
charge $Q$). Their previous analysis showed that the effects of acceleration
radiation prevent violation of the generalized second law of thermodynamics. In
our more generic case, we show that the properties of the thermal atmosphere
are equally important when charge is present. Indeed, we prove here that an
equilibrium condition for the the thermal atmosphere and the physical
properties of ordinary matter are sufficient to enforce the generalized second
law. Thus, no additional assumptions concerning entropy bounds on the contents
of the box need to be made in this process. The relation between our work and
the recent works of Bekenstein and Mayo, and Hod (entropy bound for a charged
system) are also discussed.
