What is Phase?

Getting Started• Phase can be defined as the argument of a sine or cosine function (in

a harmonic wave)• There are several formula representations of this, however the

intention of this learning object is to solidify your understanding of the basic concept first • The phase of a wave function is essentially a means of locating ‘where

on a wave you are’

Defining

• Phase is reported using Radians • An arbitrary ‘start’ point in your wave must first be defined• This point is used as reference • Use point 1 as reference• Now labels to other points can be given

Phase difference

• This is (as you would assume) the DIFFERNCE in phase between two waves

Denoted as ∆ɸQUESTION 1What is the phase difference (in radians) between the red and blue wave (shown as theta in the picture)?

Solution 1

• The easiest way to determine this is by setting two different reference points (where the two waves have the same value)• Lets pick the origin for the red wave and ∏/2 for the blue wave (at

these points both wave functions are crossing the x axis and equal) • This allows you to see that the difference in phase is simply ∏/2

Materials Cited

• http://www.3phasepower.org/images/3PhasePowerWaveF.png• http://apollo.lsc.vsc.edu/classes/remote/lecture_notes/radar/doppler

/graphics/wave_phase.free.gif