Find the final percentage of light exiting the last polizer

[matrix_204]

I was having some difficulty in solving problems, where they ask to find the final percentage of light exiting the last polizer, when three polirizers are placed on top of each other. With a certain angle between the first two polirizers and an angle between the first and the third polirizer.
please help me asap, thnx

 

[Integral]

It is no different then when 2 are present compute the output of the first pair, then use that as the input of the third. You will see some seemly strange results. If you have 2 filters at 90 deg they will block all (most) light. If you insert a 3rd filter BETWEEN the first 2 at 45 (or just something other then 90deg) you will suddenly get output from the last filter.

Sort of like the light gets twisted passing through the system.