抄録
In the experimental investigations it is usual to employ a high frequency electric field, typically several kHz, to ensure that disruption of the director orientation by conductive motion of ions is eliminated. However, in the torque-balance equation, the electric field is taken to be constant. Clearly the periodic variation in the square of the electric field will influence the director dynamics, thus as the electric field increases so the relaxation time will decrease and as the field decreases so the relaxation time will increase. In addition, the direction of the director alignment will be reversed when the electric field starts to decrease ; however the precise moment when this occurs will depend on the frequency of the electric field in comparison with the composite relaxation rate. The importance of these variations to the validity of the analysis, based on the assumption that the electric field is constant, will also depend on the frequency of the electric field and the composite relaxation rate for the director. Here, we consider this question both theoretically and experimentally.
