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Homework Help: Determining the polarisation state of the waves.

  1. Apr 24, 2012 #1
    1. The problem statement, all variables and given/known data
    [tex]E(z,t) = E_{0x} \sin (kz - wt - \frac{\pi }{12}) - E_{0y} \cos (kz - wt + \phi + \frac{\pi}{12})[/tex]
    [tex]E(z,t) = E_{0x} \sin (kz - wt - \frac{\pi }{3}) - E_{0y} \sin (kz - wt + \frac{\pi}{6})[/tex]

    3. The attempt at a solution

    For the first and second problem, I set t and z both to 0, so the only things that are left within the equations are the angles.

    I've reduced the first equation down to
    "[tex]E(z,t) = -E_{0x} \sin ( \frac{\pi }{12}) - E_{0y} \cos (\phi + \frac{\pi}{12})[/tex]"

    And I've worked out that there is a phase shift of [tex]\frac{\pi}{2}[/tex] between the waves, but I'm not sure where [tex]\phi[/tex] comes into it.

    For the second question, I've done the same process to reduce down z and t. and I've gotten [tex]E(z,t) = -E_{0x} \sin ( +\frac{\pi }{3}) - E_{0y} \sin (\frac{\pi}{6})[/tex]

    When I get here, I'm not really sure on what to do from here. I know sin's are in phase, but the angle's aren't... is it just a matter of minusing a phase angle from one another?

    I am fine with determining the actual state of polarisation because I have a table and I can also use mathematica to plot the functions out to determine it, but I'd rather use mathematics, because of how I will be examined on this.
  2. jcsd
  3. Apr 24, 2012 #2


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    Homework Helper

    What does "polarization state" mean?

  4. Apr 25, 2012 #3
    I know what polarisation state means.

    My problem is, I don't know how to work through the phase shifts, to actually find the polarization state of that specific wave.
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