  The liquid film motor (LFM) is a simple device which serves as a laboratory
to conduct experimental research in basic theoretical studies of
electrohydrodynamics (EHD). In addition the LFM can play an important role in
technological applications such as micro mixers and washers. In this paper we
initially performed experiments to examine the theory regarding rotation and
vibration of an AC LFM. While many theoretical predictions are in agreement
with our experimental data, but in the threshold of vibration there is an
obvious disagreement; we showed that no threshold exists and oscillation is
observed in any field value. Experimental evidence showed the existence of an
elastic deformation in water before reaching the yield stress and lead us to
the use of the elastic Bingham fluid model. We revised the theories using this
model and investigated the behaviour of a vibrating LFM which has more
applications in mixing. We applied a numerical solution to derive different
phases of vibration and distinguish between elastic and plastic vibrations, the
latter which could be used for mixing.
