Question regarding physical optics - (plane-polarized light)

[Sanosuke Sagara]

I have my question,solution,doubt in the attachment that followed.Thanks for anybody that spend sometime on this question.

 

[Sanosuke Sagara]

Please,I really need somebody help to explain to me what the question want so that I can have a better understanding of the question.Thanks for anybody that spend some time one this question.

 

[OlderDan]

I have my question,solution,doubt in the attachment that followed.Thanks for anybody that spend sometime on this question.

The light entering the first polarizer is already polarized. There will be an reduction in intensity that depends on the angle of the polarizer relative to the direction of light polarization at each of the polarizers. The reduction at the first polarizer will not be 1/2. It appears you know how to find the intensity reduction when polarized light passes through a single polarizer. You need to apply that twice. At the second polarizer the angle will be 30 degrees, so the final intensity will be a factor that you can calculate, based on the angle, times the intensity in the middle region. The intensity in the middle region will be a similar factor (not the same factor) times the initial intensity. You need to figure out the two reduction factors so that their product is 1/4, resolve that into the individual reduction factors, and use the intensity reduction at the first polarizer to find the angle.

I can't make sense of the answer you say is given in the book. The way it is stated appears to contradict the statement that the two polarizers are at 30 degrees relative to one another. Make sure you are looking a the correct answer.

 

[Sanosuke Sagara]

Thanks for your suggestion and the solution to this question,OlderDan and I really appreciate it.I will try to understand the question by myself.