This book will describe practical mathematical techniques to help understand circuits (mostly in the analog domain, and "medium to low" frequency) when used in transducer applications. The books’ migration path will begin with a review of some important mathematical, including some practical examples. 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. The body of the text will be constructed to that even if one doesn’t read the appendices, no flow is lost.