# Electricity, Magnetism and Circuits

## Preface

The purpose of this manual is to prepare students to understand the functioning of electrical and electronic devices that they face in their everyday experience and was written as a supporting text for the discipline of Physics 2 (EIC0014), the second year of the MSc in Engineering Informatics and computer Engineering Faculty of the University of Porto .

For several years I taught a semester of electromagnetism, for students of the second year of Engineering. In recent years introduced some changes in the program, for the best fit with the new programs of secondary education and new curricula of Integrated Masters in Engineering. An abstract approach, based on the study of Maxwell's equations, no longer fit these new curricula.

Moreover, the rapid change in technology makes some lose interest and other topics become important. For example, in the early years in which I taught eletromagnetimo, always devoted some time to explain the operation of a cathode ray tube, but did not speak liquid crystal or LED. At that time there were already LED and liquid crystal displays (LCD), but were not known by most students, while any student had a TV or monitor with a cathode ray tube. Today the situation is quite different; it is increasingly difficult to find monitors or televisions with cathode ray tubes, but we are surrounded by LCDs and LEDs. It has become more important to speak of liquid crystals or light emitting diodes than cathode ray tubes.

In this book we are used some concepts introduced in the book Dynamics and Dynamic Systems (Villate, 2015) and the Computer Algebra System (CAS) Maxima used in this book is also used here in a few chapters. The Dynamics and Dynamic Systems book is not a prerequisite for this, but it is useful to refer to it in some sections of this book that is referred to; It is also important for people who are not familiar with the Maxima system, review the appendix on the subject in this book.

In the first four chapters is made an operational introduction to electrostatics and electricity. Chapter 5 is on DC circuits. In Chapters 6 and 7 on the flow and the electrical potential is studied the electric field of more theoretical way. Chapters 8 and 9 are dedicated to the magnetic field and electromagnetic induction. Chapters 10 and 11 are also on circuit theory, but with varying tensions; Chapter 10 is an introduction to signal processing and in chapter 11 the alternating current circuits and frequency filters are studied. Finally, in Chapter 12 are studied electromagnetic waves and duality "wave-particle" of light.

In this edition 2015 we made several corrections introduced some new problems and the book format has been modified to be viewed best in phones and tablets and the PDF version can be printed in a smaller format than A4. The notation for converters has been changed and the Cartesian converters are now $\hat{\imath}$, $\hat{\jmath}$ and $\hat{k}$.

I thank especially to Professor João Rui Guedes de Carvalho, Faculty of Engineering, University of Porto, the suggestions and exchange of views on the subject and also to have made a very careful review of the book, pointing several rooks and suggesting changes to torná- it clearer. Special thanks also to all students over the past few years have contributed with comments and suggestions; your enthusiasm and interest have been a source of encouragement for writing this book; They are too many to display all their names here. I also thank the colleague John Carvalho who taught electromagnetism for several years.

Jaime E. Villate
E-mail: villate@fe.up.pt
Porto, September 2015