Surface tension reduction of liquid by applied electric field using vibrating jet method

It has been discussed in previous papers that the surface tension of some liquids decreases during voltage application, and that this could be the main mechanism for dispersion of the liquid. However, no experimental results have been reported except for a few papers. In the present study, the vibrating jet method was employed because this is a method to measure surface tension during voltage application without contacting the liquid surface. A simple procedure was developed which used a parallel sheet of laser light to detect the liquid jet waves. Surface tension reduction due to applied voltage was proportional to the square of the voltage. The measured values agreed fairly well with theoretical predictions when the electrical conductivity >10/sup -2/ S/m. The surface tension reduction calculated using the measured electric charge was also proportional to the square of the applied voltage. The mechanism causing surface tension reduction during voltage application was found to be the electric charge existing on the liquid surface.