1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Intensity of light passing through 3 polarizers

  1. Mar 8, 2017 #1
    1. The problem statement, all variables and given/known data
    Three polarizing disks whose planes are parallel and centered on common axis. The directions of their transmission axes relative to the vertical are respectively: θ1 = 33° clockwise, θ2 = 21° counter-clockwise, and θ3 = 25° clockwise. A beam of light polarized along the vertical is incident onto the first polarizer with an intensity of I0 = 26 W/m². Calculate the transmitted intensity through all three polarizers.

    2. Relevant equations
    S=S0cos2θ

    3. The attempt at a solution
    I recognize that the light passing through the polarizers has already been polarized. To find the intensity of the light that passes through the first polarizer I used Malus' Law and used the angle 33°. I am not sure how to deal with the angles of the remaining two polarizers to find the total transmitted intensity through all three polarizers.

    EDIT: The angle θ is the angle made between the axis of polarization of the light and axis of transmission of the polarizer. According to that logic I came up with the conclusion that

    I0cos2(33)cos2(54)cos2(46)

    54 is the angle made between 33° clockwise and 21° counter-clockwise, and 46 is the angle made between 21° clockwise and 25° clockwise
     
    Last edited: Mar 8, 2017
  2. jcsd
  3. Mar 8, 2017 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Good.

    Do the same thing, only realize that after the beam passes through the first polarizer it is polarized in a new direction, given by the angle of the polarizer. Treat each passing the same way.
     
  4. Mar 8, 2017 #3
    The light incident on the seconds polarizer is also polarized - but not along the vertical axis. What is it's angel relative to the second polarizer?
     
  5. Mar 8, 2017 #4

    Doc Al

    User Avatar

    Staff: Mentor

    Good!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted