Difference in polarization with birefringence substance and polarization filter

  1. Hi there.
    Sorry for my poor English first.

    I have been reading chapter about polarization in Feynman Lectures on Physics.

    There is a experiment about polarization using 2 polaroids and birefringence cellophane located between two polaroids.
    optic axis of two polaroids are 0 and 90 in degree, and cellophane's is 45 in degree.
    As you know, polarized light can travel through the three substances.
    According to my view, it can be explained by using birefringence property of cellophane.
    In Feynman lectures, birefringence can be explained by demonstrating arrangement of molecule and its way of accelerating electrons. in my view, it seems superficially that it isn't with probability problems.

    But what about this case?
    http://alienryderflex.com/polarizer/

    this experiment uses three polaroids. it saids, it can be explained by using probability theory.

    In these situations, What similarity do cellophane in the first experiment and middle polaroid in the second experiment have?

    regards and sorry for my poor English again.
     
  2. jcsd
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