Our objective was primarily to consider in a separate treatise from the general point of view a theory of as many electrodynamic phenomena in a magnetic field as possible. The choice of material was determined by both the ab­ sence of such a book and the scientific interests of the authors. From the very beginning, however, we felt it necessary to include the fundamentals of electrodynamics that are required for the thorough analysis of particular processes. We believe that it is convenient for a reader to find in the same book a consistent review of some special fields in physics and a complete set of theoretical instruments that are necessary for the clear understanding of more advanced parts of the book. There exists a number of excellent textbooks and monographs describing the problems of classical electrodynamics in general and its applications to continuous media. We have to acknowledge, for example, the following funda­ mental books: Electrodynamics by A. Sommerfeld [1], The Classical Theory of Fields by L.D. Landau and E.M. Lifshitz [2], Electromagnetic Theory by J.A. Stratton [3], and Electrodynamics of Continuous Media by L.D. Lan­ dau and E.M. Lifshitz [4]. This list is certainly not exhaustive. However, to our knowledge, a book specifically covering the theory of electrodynamic phenomena in a magnetic field has not yet been written.