Ultrasonic Wave Propagation Velocity in Nonconducting Liquids in an External DC Electric Field

Abstract

A theoretical analysis of variations in the propagation velocity of ultrasonic waves in liquid dielectrics in an external DC electric field was performed. Measurements of these variations in transformer oil in dependence on the field strength and temperature were made applying the phase method. To express the experimental results in graphical form numerical procedure of interpolation in Lagrange polynomials was used. The experimentally obtained variations in the velocity are compared with those predicted theoretically by the formulae derived.PACS numbers: 43.35.+d Effect of an external DC electric field on the ultrasonic propagation velocity in nonconducting liquidsFrom the point of view of thermodynamics, in order to measure the ultrasonic propagation velocity, the system has to be led to equilibrium; the equations of electrostatics are then fulfilled [1]. With regard to the Helmholtz formula [2,3] for the square of the propagation velocity of an acoustic wave:where F is the molar free energy and V -the molar volume of the liquid, we have to find the form of the free energy F of the system as a function of state. The general formula is well known from thermodynamics, where the total free energy of (683)