A sinusoidal function of the type often used in fields is
f 1ðx; y; z; tÞ ¼ A0
x, y, z
cos
ωt þ θ
or f 2ðx; y; z; tÞ ¼ A0
x, y, z
sin
ωt þ θ
ð11:60Þ
The phasor notation now allows us to write
A0ðx; y; zÞcosðωt þ θÞ ¼ Re A0ðx; y; zÞe jωte jθ
ð11:61Þ
A0ðx; y; zÞsinðωt þ θÞ ¼ Im A0ðx; y; zÞe jωte jθ
ð11:62Þ
where A0 is real and independent of time, Re{ } means the real part of the function, and Im{ } means the imaginary part of
the function. Finally, we define the phasor as that part of the function which does not contain time; that is,
Apðx; y; zÞ ¼ A0ðx; y; zÞe jθ ð11:63Þ
This is sometimes written as an amplitude and phase as
Apðx; y; zÞ ¼ A0ðx; y; zÞ∠θ ð11:64Þ
Summarizing, the phasor can be written in three different forms:
Apðx; y; zÞ ¼ A0ðx; y; zÞe jθ ¼ A0ðx; y; zÞ∠θ ¼ A0ðx; y; zÞcosθ þ jA0ðx; y; zÞsinθ ð11:65Þ
The first form is called the exponential form, the second is the polar form, and the third is the rectangular form. Most
of our work in this book will be carried out in the exponential form. On occasion, we will use the polar form, particularly