Newnes Circuit Calculations Pocket Book

12 Phasors

12.1

Introduction

Chapter 11 showed that problems in a.c. circuits can be solved using

phasors. A phasor has both magnitude and direction and it can be

resolved into two components at right angles to each other. Figure

12.1 shows a phasor OA, and this can be written as

x + }y

O x

Figure

12.1

x is the horizontal component, and the operator / is introduced to

indicate that the other component is along the y axis.

x + jy is called a complex number, x, the horizontal component, is a

real number. If the vertical component is an imaginary number,

Figure 12.1 shows that the length of the phasor OA is

V(*

2

+ y

2

) (modulus)

and the phase angl ...