Does the generalized second law require entropy bounds for a charged system?

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-Nordström black hole and then its contents are released into the black hole. Originally, it had been thought that this process with Q=0 might violate the generalized second law of thermodynamics. However, Unruh and Wald showed that the effects of acceleration radiation prevent violation of the generalized second law. In our more generic case with the charged contents of the box, we show that the properties of the thermal atmosphere play an equally important role as a neutral box case. Indeed, we prove here that an equilibrium condition for the thermal atmosphere and the physical properties of ordinary matter are sufficient to enforce the generalized second law. Thus, no additional assumptions concerning the entropy bounds on the contents of the box need to be made in this process. The relation between our results and the recent work by Bekenstein and Mayo [Phys. Rev. D 61, 024022 (2000)], and Hod [gr-qc/9903010; Phys. Rev. D 61, 024023 (2000)] on entropy bounds for charged systems are also discussed.