Physics Help Forum Polarization

 Dec 14th 2009, 08:54 AM #1 Junior Member   Join Date: Dec 2009 Posts: 21 Polarization Three polarized placaas are superimposed. The first and third are crossed. The polarization direction of the plate means is 45 ° with the directions of polarization of the other two. What fraction of the intensity of the beam initially non-polarized is transmitted by the system boards?
 Dec 14th 2009, 09:40 AM #2 Senior Member   Join Date: Oct 2009 Location: india Posts: 409 malus law application will give u 1/8. but where is your attempt, friend?
Dec 14th 2009, 11:18 AM   #3
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 Originally Posted by r.samanta malus law application will give u 1/8. but where is your attempt, friend?

Malus is:
I = I_m cos^2 \theta

I did not understand the problem. Why can not I see the direct application

 Dec 15th 2009, 06:50 AM #4 Senior Member   Join Date: Oct 2009 Location: india Posts: 409 SINCE initially light is unpolarised, first polariser will just pass half the intensity (resolve all E along pass axis and u will see why) second one allows I/2 cos ^2 theta third one allows I/2 cos ^2 theta cos^2 theta put theta. it is 45 in this case for both.
Dec 15th 2009, 08:04 AM   #5
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 Originally Posted by r.samanta SINCE initially light is unpolarised, first polariser will just pass half the intensity (resolve all E along pass axis and u will see why) second one allows I/2 cos ^2 theta third one allows I/2 cos ^2 theta cos^2 theta put theta. it is 45 in this case for both.

Oh yes, thank you

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