On the basis of dielectric relaxation of charge in the conducting medium a principle of repulsion, which has a special significance when is applied to electrically neutral medium, is formulated. It is shown that ions of conducting medium with excessive mobility are repulsed from conducting volume, creating some nonzero charge density on its boundaries. Application of the repulsion principle allows to give an evident physical interpretation to some well-known phenomena: generation of thunderstorm lightning, formation of atmospheric electricity and mist precipitation, Earth’s magnetism and clarification of the role of magnetic field in the activity of biochemical reactions in the biological cell. A special part of the repulsion principle in the vital activity of the biological cells, namely cell exchange and maintenance of electrical potential on the membrane, cells interaction and genetic peculiarities of cancer cells generation, is revealed. The question of membrane transport and principle of the work of cell ionic pump is clarified. A simple mathematical model of cell transport stabilization is proposed. Main characteristics of the cell exchange, conditions of provision of cells with oxygen, and reasons of the cells death owing to cell exchange disturbance are revealed. The possibilities of direct activation of biochemical, intracellular reactions by external magnetic influence and production of biological tissue controlled by cell exchange out of living organism are shown.