Newnes Circuit Calculations Pocket Book

Phasors 225

Note

3.61 x 4.12 756.31° - 14.04° = 14.87 742.27°

Multiplication in polar form is considerably easier than multiplying

in rectangular from.

12.5 Division

Division can be carried out using either the rectangular or the polar

form.

In the rectangular form the expression is rationalized by multiplying

the numerator and the denominator by the conjugate of the

denominator thus

a + jb _ {a + jb)(c - jd)

c + jd (c + jd)(c - jd)

ac + jbc - jad -

j

2

bd

c

2

+ jcd - jcd -

j

2

d

2

ac + jbc - jad + bd

c

2

+ d

2

Note c - jd is the conjugate of c + jd.

j

2

= -1 see Section 12.1

In the polar form

N 7e°

since y

M

<l>

0

Example 18 Evaluate

2 + j9

5-/2

10