phase

phase: 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. Note 1: Phase, i.e., phase time (frequently abbreviated simply to "phase" in informal 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&176; (2

radians). Note 3: Phase may be represented (a) in polar coordinates by M

, where M is the magnitude and

is the phase angle, and (b) in Cartesian coordinates, i.e., an Argand diagram, as (a + jb), where a is a real component and b is an imaginary component such that tan

= (b /a), where

is the phase angle, and the magnitude, M, is (a ²+ b ²)^½ 2. A distinguishable state of a phenomenon. 3. That period of time during which a specified function occurs in a sequential list of functions.