  Several active galactic nuclei and microquasars are observed to eject
plasmoids that move at relativistic speeds. We envisage the plasmoids as
pre-existing current carrying magnetic flux ropes that were initially anchored
in the accretion disk-corona. The plasmoids are ejected outwards via a
mechanism called the toroidal instability (TI). The TI, which was originally
explored in the context of laboratory tokamak plasmas, has been very successful
in explaining coronal mass ejections from the Sun. Our model predictions for
plasmoid trajectories compare favorably with a representative set of
multi-epoch observations of radio emitting knots from the radio galaxy 3C120,
which were preceded by dips in Xray intensity.
