  We study the properties of the loosely trapped surface (LTS) and the
dynamically transversely trapping surface (DTTS) in Einstein-Maxwell systems.
These concepts of surfaces were proposed by the four of the present authors in
order to characterize strong gravity regions. We prove the Penrose-like
inequalities for the area of LTSs/DTTSs. Interestingly, although the naively
expected upper bound for the area is that of the photon sphere of a
Reissner-Nordstroem black hole with the same mass and charge, the obtained
inequalities include corrections represented by the energy density or
pressure/tension of electromagnetic fields. Due to this correction, the
Penrose-like inequality for the area of LTSs is tighter than the naively
expected one. We also evaluate the correction term numerically in the
Majumdar-Papapetrou two-black-hole spacetimes.
