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Polarization of clear plastic - a puzzle

  1. Jan 27, 2015 #1
    I finished my online E&M class today, and the prof told us to experiment with polarizers. While doing that, I found this: I put a piece of plastic between two polarizers, and found that at a certain angle between the two polarizers, a portion - though not all - of the plastic darkened. So I assumed that portion of the plastic sheet was a polarizer, for whatever reason. And I also assumed that a single polarizer, when used with this piece of plastic, would show darkening. But when I used a single polarizer, nothing happened, no matter how I rotated the polarizer. So that means the plastic actually is not a polarizer, right? So what was going on when it was between the two polarizers? This piece of plastic happens to be semi-transparent red gift wrap, if that helps.
  2. jcsd
  3. Jan 27, 2015 #2

    Andy Resnick

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  4. Jan 28, 2015 #3
    Thanks Andy. So it sounds like I need to read up on wave retarders. I'll take a look at the plastic again later today.
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