This first volume provides the teaching material for both the introductory part of the lecture "Fundamentals of Electrical Engineering" and for the elective courses on electrical engineering from other degree programs. The focus of the work is on network theory and the detailed derivation of the physical principles. The methods presented also form the basis for understanding more advanced courses. To familiarize oneself with the material, it is advisable to solve the exercises listed at the end of the book. Sample solutions are provided. For the 5th edition, the content has been adapted to the latest developments in the field.