The magneto-optic effects in magnetic emulsions with low interfacial tension based on aviation hydraulic oil and in magnetic colloids with an extensive system of nanoparticle aggregates is investigated. The effect of changing the transparency in a longitudinal magnetic field is detected, the magnitude of which can be controlled by changing the strength and orientation of the magnetic field. In a transverse field, the effect of anisotropic diffractive scattering of light by irregular and regular systems of microdroplets elongated along the field is demonstrated. Diffraction patterns are obtained that can be configured by adjusting the ratio of components of a rotating magnetic field. It is concluded that magnetic emulsions and magnetic colloids with concentrated nanoparticle aggregates are promising as materials for magnetically controllable optical elements.

The anisotropy of magnetic emulsions induced by simultaneously acting electric and magnetic fields is theoretically and experimentally investigated. Due to the anisotropy, the electric conductivity and magnetic permeability of a magnetic emulsion are no longer scalar coefficients, but are tensors. The electric conductivity and magnetic permeability tensors of sufficiently diluted emulsions in sufficiently weak electric and magnetic fields are found as functions of the electric and magnetic intensity vectors. The theoretically predicted induced anisotropy was verified experimentally. The experimental data are fitted in order to calculate the dimensions of the ellipsoidal drops of the emulsion distorted by the electric and magnetic fields. The dependence of the calculated fitting parameter on the intensity of the magnetic field is compared with the theoretical one. The results of the analysis of the experimental data are discussed.