Studies of sessile droplets and fluid bridges of a ferroelectric nematic
liquid crystal in externally applied electric fields are presented. It is found
that above a threshold a fingering instability occurs, resembling to
Rayleigh-type instability observed in charged droplets in electric fields or
circular drop-type instabilities observed in ferromagnetic liquids in magnetic
field. The frequency dependence of the threshold voltage was determined in
various geometries. The nematic director and ferroelectric polarization
direction was found to point along the tip of the fingers that appear to repel
each other, indicating that the ferroelectric polarization is essentially
parallel to the director. The results are interpreted in analogy to the
Rayleigh and circular drop-type instabilities