Electrically Driven Resonant Oscillations of Pendant Hemispherical Liquid Droplet and Possibility to Evaluate the Surface Tension in Real Time

Abstract The influence of the supporting surface on the resonant frequency of pendant droplets has been examined experimentally. It has been shown that for spherical pendant droplets the correction term due to the boundary conditions at the supporting surface depends on the geometry and material of the supporting element, but also on the liquid of the droplet, which makes calibration impossible. In contrast, for hemispherical pendant droplets the influence of the boundary conditions can be kept constant and can be eliminated after calibration. A method for measuring the surface tension in real time from the resonant frequency of a hemispherical droplet has been proposed and errors have been evaluated.</jats:p

Oscillating bubble as a sensor of low frequency electro-acoustic signals in electrolytes

Small air-bubble deformations, caused by electro-acoustic signals generated in electrolytic solutions have been detected by angle-modulation of a refracted He Ne laser beam. The observed electromechanical resonance at low frequency, below 100 Hz, has proved to be directly related to the oscillations of characteristic ion-doped water structures when driven by an external electric field. The presence of structure-breaking or structure-making ions modifies the water structure, which varies the mechanical losses of the oscillating system and can be registered as changes in the width of the observed resonance curves

Surface thermoelastic deformations caused by a laser

A method is suggested for an accurate experimental measurement of the topography of the surface thermoelastic deformations in solids, induced by a point focused CW laser beam. An approximate theory for the surface deformation of anisotropic materials is obtained. Different cuts of quartz and glass samples have been examined