DETERMINATION OF SURFACE-TENSION FROM THE SHAPE OSCILLATIONS OF AN ELECTROMAGNETICALLY LEVITATED DROPLET

In the fundamental (l=2) mode, the frequency spectrum of a magneticall y levitated inviscid droplet exhibits three distinct peaks. If the mod es that correspond to each of these peaks is known, the surface tensio n of the droplet may be calculated. In experiments that make use of th is principle, there is no unambiguous method of assigning mode numbers to these peaks. The dynamics of the oscillating droplet depend on the magnetic pressure on the droplet surface. Consequently, the order of the peaks in the l=2 mode oscillations is determined by the magnetic p ressure distribution. In this paper, the magnetic pressure distributio n on the surface of the droplet is calculated as a function of the par ameters that govern the external magnetic field. The frequencies of th e droplet oscillation and its static shape deformation are also expres sed in terms of these same parameters. The frequencies of oscillation are used to determine the surface tension of the liquid droplet. Final ly, the magnetic pressure distribution on the droplet is shown to yiel d the well-known ''pear-like'' shape that is assumed by liquid metal d roplets in a conical levitator. (C) 1996 American Institute of Physics .