Macroscopic friction and dielectric relaxation

Dielectric relaxation is known to depend on whether the process is controlled by field strength or by charge density. The aim of this study is to give mechanical meaning to the constant field (or transversal) relaxation time tau and the constant charge (i.e. constant displacement or longitudinal) relaxation time theta . First, it is demonstrated that the formal difference between field and charge control disappears if the perturbation is periodic. Then tau is shown to be the relaxation time of the transient torque applied to the system by the change of the direction of the field. Similarly, theta is the relaxation time of the deformation force in the dielectric substance brought about by a sudden change of the external field. By this token, both relaxation times are recognized as quantities proportional to the reciprocal internal friction coefficients of the substance, tau being connected with rotation and theta with translation.<
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