1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    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!

What is the intensity of the incident of light?

  1. Apr 1, 2009 #1
    1. The problem statement, all variables and given/known data

    Unpolarized light is incident on a system of three polarizers. The second polarizer is oriented at an angle of 28.0° with respect to the first and the third is oriented at an angle of 45.0° with respect to the first. If the light that emerges from the system has an intensity of 2.1 W/m2, what is the intensity of the incident light?

    2. Relevant equations

    is this what you do: 2.1W/m^2 divided by cos^2(21). then divide that answer by cos^2(28) than multiply that anwswer by 2? I can's eem to get the right anwser to cos2(21) and cos2(28) right in my calculator. I need some help

    3. The attempt at a solution
  2. jcsd
  3. Apr 1, 2009 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    You're right except for the 21o. What is the angle between the 2nd and 3rd polarizers?

    (Good job catching the final 2x factor, a lot of people miss that on problems like this.)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook