within an electrolyte bath in fig2 a the electrical connections for three phase operation are shown essentially a single specimen was connected to each electrode and the electrodes were in turn connected to the output terminals of a three phase generator in fig2 b the oscilloscope traces of voltage and current are shown the upper trace represents the voltage v and the lower trace the current i while the supply voltage was pure sinusoidal i e without waveform distortion the voltage across the electrodes while the process was in progression was slightly distorted by contrast the current waveform has higher harmonics as the supplied sinusoidal voltage raises from zero to a maximum the current does not follow the voltage signal for a short time the current is zero this is due to the fact that a certain minimum voltage is required for the current to break through the oxide film this voltage may be called threshold voltage once the film is broken though the current signal rises in unison with the voltage across the electrodes as the voltage falls from the peak value the current too falls however the current falls to zero sooner than the voltage due to the threshold effect it may be noted that the specimens become oxidized during the positive half cycle of the supplied voltage during the negative half cycle the oxide film is sintered and consolidated to form an adherent dense coating to bond with the substrate the true oxidation time per cycle however is only a half of the half cycle time similar observations have been made with single phase operation also the primary difference however is that in the single phase operation the voltage and current will be in phase whereas.