INTRODUCTION

Alternating supply is invariably used for domestic and industrial applications. The path for the flow of alternating current is called an AC circuit. In DC circuits, the opposition to the flow of current is only the resistance of the circuit. While in AC circuits, the opposition to the flow of current is due to resistance (R), inductive reactance (X_L = 2π fL) and capacitive reactance (X_C = 1/2 πfC) of the circuit. In AC circuits, frequency plays an important role. In these circuits, the currents and voltages are represented with magnitude and direction (phasors). The voltage and current may or may not be in phase with each other depending upon the parameters (R, L, and C) of the circuit. Moreover, in AC circuits, the currents as well as voltages are added and subtracted vectorially instead of arithmetically as in DC circuits. Hence, AC circuits need more attention for their solution. In this chapter, we shall confine our attention to the fundamentals related with various types of AC circuits.