The electric field at a water surface stressed by an AC voltage

Oscillating projections can develop on the surface of a conductive liquid stressed by a perpendicular, alternating electric field. In this work, a water surface was confined in a narrow channel, resulting in a single row of projections, allowing good observations of the projection shapes. This paper discusses the experimentally observed development of the projections, and the resulting electric field at their tips. The row of projections behaves as a standing wave at the frequency of the applied AC voltage. It was seen that the formation of the projections, and hence the maximum electric field, lags the applied voltage. The normally rounded projections can become conical if the voltage is high enough for sparking to occur. Sparking was observed to occur as the applied voltage declined from its peak, corresponding to the time of the calculated maximum electric field