1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Finding Incident Intensity for Unpolarized Light

  1. Sep 8, 2009 #1
    1. The problem statement, all variables and given/known data
    Two sheets of Polaroid are placed on top of each other with an angle φ between their pass
    directions. Calculate be the ratio of transmitted to incident intensity for initially unpolarised
    light if φ = 30°.

    I copied the question exactly, I'm pretty sure that typo wasn't on purpose but I left it there anyway.

    2. Relevant equations

    I0 = I'/2

    Malus's Law
    I = I0 cos^2 θ

    3. The attempt at a solution

    I used the equation above to do:

    = I0 cos^2(30)
    .75 x .75 = .5625 = 9/16
    = I0(9/16)

    not sure if that is right
    Last edited: Sep 8, 2009
  2. jcsd
  3. Sep 8, 2009 #2


    User Avatar
    Homework Helper

    When the unpolarised light is transmitted through a Polaroid, 50% of light is transmitted. So I' = Io/2
    When it passes through second Polaroid, the intensity of transmitted light is
    I" = Io/2*cos^2(θ)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook