Phase refers to the location within a wave cycle. It is measured in radians and defines a starting reference point to describe where other points are located within the wave. The phase difference between two waves is the difference in phase between them, denoted by Δφ. For example, between a red and blue wave shown in a picture, the phase difference is π/2 radians because the blue wave is shifted by π/2 radians compared to the red wave.

1. What is Phase?

2. 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’

3. 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

4. Phase difference
• This is (as you would assume) the DIFFERNCE in phase between two
waves
Denoted as ∆ɸ
QUESTION 1
What is the phase difference (in radians)
between the red and blue wave (shown as
theta in the picture)?

5. 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

6. Materials Cited
• http://www.3phasepower.org/images/3PhasePowerWaveF.png
• http://apollo.lsc.vsc.edu/classes/remote/lecture_notes/radar/dopple
r/graphics/wave_phase.free.gif