Introduction

 Introduction

• Electromagnetics is a branch of physics or electrical engineering which is used to study the electric and magnetic phenomena. The electric and magnetic fields are closely related to each other.

• Let us see, what is a field ? Consider a magnet. It has its own effect in a region surrounding it. The effect can be experienced by placing another magnet near the first magnet. Such an effect can be defined by a particular physical function. In the region surrounding the magnet, there exists a particular value for that physical function, at every point, describing the effect of magnet. So field can be defined as the region in which, at each point there exists a corresponding value of some physical function.

• Thus field is a function that specifies a quantity everywhere in a region or a space. If at each point of a region or space, there is a corresponding value of some physical function then the region is called a field. If the field produced is due to magnetic effects, it is called magnetic field. There are two types of electric charges, positive and negative. Such an electric charge produces a field around it which is called an electric field. Moving charges produce a current and current carrying conductor produces a magnetic field. In such a case, electric and magnetic fields are related to each other. Such a field is called electromagnetic field. The comprehensive study of characteristics of electric, magnetic and combined fields, is nothing but the engineering electromagnetics. Such fields may be time varying or time independent.

• It is seen that distribution of a quantity in a space is defined by a field. Hence to quantify the field, three dimensional representation plays an important role. Such a three dimensional representation can be made easy by the use of vector analysis. The problems involving various mathematical operations related to the fields distributed in three dimensional space can be conveniently handled with the help of vector analysis. A complete pictorial representation and clear understanding of the fields and the laws governing such fields, is possible with the help of vector analysis. Thus a good knowledge of vector analysis is an essential prerequisite for the understanding of engineering electromagnetics. The vector analysis is a mathematical shorthand tool with which electromagnetic concepts can be most conveniently expressed.

• This chapter gives the basic vector analysis required to understand engineering electromagnetics. The notations used in this chapter are follwed throughout this book to explain the subject.