This book will be an exposition describing practical mathematical techniques to help understand circuits when used in transducer applications. The circuit types will be mostly in the analog domain, and “medium to low” frequency. Some examples of the transducers will be solenoids, loudspeakers, and capacitive sensors. The books’ migration path will begin with a review of some important mathematical concepts that need to be understood for the proceeding chapters. This will include some practical examples to help reinforce the spirit. When heading into the physics, the practical examples will be more or less turned into the subject material. The physics will start from the basic relationships between electric & magnetic fields, and how they result from circuits that generate them. Field interactions will be discussed and analyzed, to create an understanding of how the forces present themselves as a useful tool. This will also help explain how the transducers influence the circuit behavior. Much of the higher level equations will be presented and described in detail. There will be many footnotes referring the reader to appendices that will contain the full derivation. This will quench the thirst for the very curious and ambitious readers who want a deep understanding.