1. Of a periodic, varying phenomenon,
e.g., an electrical
signal or
electromagnetic wave, any distinguishable instantaneous state of the phenomenon, referred to a fixed reference or another periodic varying phenomenon. (
188 )
Note 1: Phase,
i.e., phase time (frequently abbreviated simply to "phase" in colloquial usage), can be specified or expressed by
time of occurrence relative to a specified reference.
Note 2: The phase of a periodic phenomenon can also be expressed or specified by angular measure, with one period usually encompassing 360° (2
![](http://info.babylon.com/onlinebox.cgi?rt=GetFile&uri=!!XVQ3V8DTBT&type=0&index=88)
radians).
Note 3: Phase may be represented (a) in polar coordinates by
M ![](http://info.babylon.com/onlinebox.cgi?rt=GetFile&uri=!!XVQ3V8DTBT&type=0&index=32)
![](http://info.babylon.com/onlinebox.cgi?rt=GetFile&uri=!!XVQ3V8DTBT&type=0&index=144)
, where
M is the magnitude and
![](http://info.babylon.com/onlinebox.cgi?rt=GetFile&uri=!!XVQ3V8DTBT&type=0&index=144)
is the
phase angle, and (b) in Cartesian coordinates,
i.e. , an Argand diagram, as (
a + j
b ), where
a is a real
component and
b is an imaginary component such that tan
![](http://info.babylon.com/onlinebox.cgi?rt=GetFile&uri=!!XVQ3V8DTBT&type=0&index=144)
= (
b /
a ), where
![](http://info.babylon.com/onlinebox.cgi?rt=GetFile&uri=!!XVQ3V8DTBT&type=0&index=144)
is the phase angle, and the magnitude,
M , is (
a 2 +
b 2)
½ 2. A distinguishable state of a phenomenon. (
188 )
3. That period of time during which a specified function occurs in a sequential list of functions. (
188 )