  We show that several novel effects related to persistent currents can arise
in open systems, which have no analogue in closed or isolated systems. We have
considered a system of a metallic ring coupled to two electron reservoirs. We
show that in the presence of a transport current, persistent currents can flow
in a ring even in the absence of magnetic field. This is related to the current
magnification effect in the ring. In the presence of magnetic field we show
that the amplitude of persistent currents is sensitive to the direction of
current flow from one reservoir to another. Finally we briefly discuss the
persistent currents arising due to two nonclassical effects namely,
Aharonov-Bohm effect and quantum tunneling.
