Shape Stability of Magnetic Fluid

A study of the instability of a spheroidal droplet of magnetic fluid in a uniform magnetic field, without a gravitational field, is described. A droplet of ferrofluid was suspended in water or glycerin, the droplet minor axis was measured for fields up to 1.2 kOe, and the interfacial tension between the ferrofluid and the water or glycerin was determined. The ratio of the droplet major axis to the minor axis K^¿1 increased with increasing field, and depended on the initial droplet diameter. The results could be explained by minimizing the sum of the magnetic energy and the surface energy with respect to K.