An investigation was carried out on frequency behavior of the complex electric modulus, the impedance and the conductance, related to the displacement current resulting from the normal Brownian dynamics of relaxing molecular dipoles in dielectric materials. The experiment was performed for the liquid crystalline smectic A phase of n-octylcyanobiphenyl (8CB) in the frequency region of 200 kHz-50 MHz, where the single dielectric relaxation of the Debye-type occurs and, at the same time, the ionic conductivity in the compound is negligibly low (sigma(DC) approximate to 0).