We consider the general form of the transient signals which arise in a de conductivity cell when dipoles are photoinduced in a liquid solution by laser excitation. The formalism is based on the solution of Debye’s equation for rotating molecules but includes a time-variable concentration of dipoles. Onsager’s treatment of the internal field acting on the dipoles is used. It is shown that, given adequate time resolution, this method allows measurement of the rotational time, the lifetime, and the dipole moment of various excited states. When the ground state is dipolar, the signal is shown to depend on the polarization of the light with respect to the applied electric field. Variation of the light polarization in such an experiment increases the accuracy of derived parameters and : even allows the ground state dipole moment to be measured. Results depend substantially on the shape of the dipolar species. An extension of Onsager’s treatment to the case of an ellipsoidal cavity is applied to the problem. Approximations to the general result for an ellipsoidal cavity are also given.