RESONANCE-ABSORPTION OF THE ULTRASONIC-WAVES IN MAGNETIC LIQUIDS IN DC MAGNETIC-FIELD

An external magnetic field, applied to a magnetic fluid, gives rise to spherical and chain-like clusters. The present paper is based on an a coustic method permitting the determination of the presence and size o f the clusters by having recourse to resonance absorption of an ultras onic wave in a magnetic fluid acted on by a magnetic field. We report our measurements of the variations Delta alpha of the ultrasonic absor ption coefficient for three frequencies of the wave in a selected magn etic fluid versus the external magnetic field strength applying the pu lse method. (C) 1998 Elsevier Science B.V.