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PLease help with polarizer/intensity question

  • Thread starter Sgtsloth
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  • #1
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SunBUpB.png


So I know the equation:

Itrans = I0 Cos2θ

Since this light starts out as polarized, there is no need to cut it in half like you do for unpolarized light. So I did the equation through the first polzarizer, using 30 degree as my angle, and came out with I=0.75

Now I used that 0.75 as my new I0 as the light went through the 2nd polarizer, this time I used 60 degrees as my θ and I got 0.1875, which would be B.

However, I saw the same problem elsewhere where the guy got D) as the answer because he used 30 for θ instead of 60.
 

Answers and Replies

  • #2
blue_leaf77
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I agree with you.
 
  • #3
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edit: I didnt notice the opposite axis of the second one, I would say you are correct in your first assumption and I agree with the rest of the posters. use 30 then 60
 
Last edited:
  • #4
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Since you have 2 polarized sheets at 30 degree I would use 1(cos30^2)^2
That gives 0.5625, can you explain WHY you would use 30 degree for the second polarizer when the axis is 60 after the coming out of the first one?
 
  • #5
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Anyone else want to chime in, I still don't know which is correct.
 
  • #6
TSny
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Anyone else want to chime in, I still don't know which is correct.
B is the right answer. Your analysis of using 30 then 60 degrees is correct.
 
  • #7
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B is the right answer. Your analysis of using 30 then 60 degrees is correct.
Thank you
 

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