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. ( 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 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 + j b ), 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. ( 188 ) 3. That period of time during which a specified function occurs in a sequential list of functions. ( 188 )