This book is intended to serve as a textbook for courses in engineering physics, and as a reference for researchers in theoretical physics with engineering applications introduced via study projects, which will be useful to researchers in analog and digital signal processing. The material has been drawn together from the author's extensive, interpreting the classical theory of Landau and Lifschitz. The methosdology employed is to describe the physical models via ordinary or partial differential equations, and then illustrate how digital signal processing techniques based on discretization of derivatives and partial derivatives can be applied to such models.