Electrorheology in liquids and liquid crystals studied by ultrasonic wave

The electrorheology (ER) effect in liquids and liquid crystals are investigated by ultrasonic wave propagation. The acoustic phase-delay change, which is related to the ultrasonic wave velocity, is related to the viscosity of liquids and liquid crystals. The applied voltage dependence of acoustic phase-delay change in nematic liquid crystal, the ferroelectric liquid crystal and silicone oil are measured. The ER effect in liquid and liquid crystals are discussed in the viewpoint of liquid-crystal director orientation.