In this paper, we study the persistent current in a normal conductor ring coupled to a reservoir with an ideal lead and investigate the effect of an electromagnetic potential on free electrons in a normal-conductor one-dimensional ring. The electrostatic potential on the ring modulates the amplitude, phase and frequency of the Aharonov-Bohm flux current. We discuss the effect of reflection on both sides of the gate electrode on the persistent current in the presence of an electromagnetic potential. The oscillation amplitude of the persistent current and the density of states decrease as the electrostatic potential increases at constant magnetic flux.