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Determine the rms value of the electric field of the transmitted beam

  1. Dec 5, 2009 #1
    1. The problem statement, all variables and given/known data

    A beam of polarized light has an average intensity of 13.2 W/m2 and is sent through a polarizer. The transmission axis makes an angle of 27.5° with respect to the direction of polarization. Determine the rms value of the electric field of the transmitted beam.


    2. Relevant equations



    3. The attempt at a solution
    This is what I have done to try this problem:
    I used Erms = square root of: [I(4pi * 10^-7)(3 x 10^8)]
    I used I = Iocos^2theta
    I = (13.2)(cos27.5)^2
    I = 10.3856

    According to the homework program I am using, the answer I have gotten is not correct...I am not sure what I am doing wrong. Thanks in advance!
     
  2. jcsd
  3. Dec 6, 2009 #2

    Redbelly98

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    I agree with your value of I=10.4 W/m^2.
    Can you post your calculation of Erms?
     
  4. Dec 6, 2009 #3
    I have finally solved it! So my Erms equation was correct. My intensity was not...
    Turns out what I had to do was not square the cos...
    so instead of I = Iocos227.5
    the equation is:
    I = Iocos27.5 = 11.7085

    Which I can then plug into the equation for Erms above

    Thanks for your help!
     
  5. Dec 6, 2009 #4

    Redbelly98

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  6. Dec 6, 2009 #5
    yeah, I know...but our homework is on a computer program (CAPA), and after using 7 out of 10 tries on this problem I called a classmate and he said that he did it without the cos squared...so I tried it and it was finally marked correct!...not really sure what's going on with this problem!
     
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