# Field Theory Notes eBook

**DIWALI2017**

- Description

### About this eBook

Introduction to Field Theory The behavior of a physical device subjected to electric field can be studied either by Field approach or by Circuit approach. The Circuit approach uses discrete circuit parameters like RLCM, voltage and current sources. At higher frequencies MHz or GHz parameters would no longer be discrete. They may become non linear also depending on material property and strength of v and i associated. This makes circuit approach to be difficult and may not give very accurate results. Thus at high frequencies, Field approach is necessary to get a better understanding of performance of the device. FIELD THEORY The Vector approach provides better insight into the various aspects of Electromagnetic phenomenon. Vector analysis is therefore an essential tool for the study of Field Theory. The Vector Analysis comprises of Vector Algebra and Vector Calculus . Any physical quantity may be Scalar quantity or Vector quantity . A Scalar quantity is specified by magnitude only while for a Vector quantity requires both magnitude and direction to be specified. Examples Scalar quantity Mass, Time, Charge, Density, Potential, Energy etc., Represented by alphabets A, B, q, t etc Vector quantity Electric field, force, velocity, acceleration, weight etc., represented by alphabets with arrow on top.

A, B, E, B etc.,

Vector algebra If A, B, C are vectors and m, n are scalars then

1 Addition

A B B

A B C

A

A B C

Commutative law Associative law

2 Subtraction

A - B A - B 3 Multiplication by a scalar