This is a high-school level question, I think. But I'm in high school
We are told that a polaroid filter will only allow light to pass if it is polarized on the same axis as the filter. Otherwise, it will not get through. It follows, then, that if you pass light through two polaroid filters, you will get nothing through the other side. Empirically, we can test this, and it confirms what we know.
So far so good.
Now, say we take a third filter and put it in between the two previous ones. We turn it to a 45-degree angle from both of them. Now, if no light could get through the two filters before, then surely adding a filter would not change this. After all, a filter cannot generate or re-polarize light, right?
But if we actually perform this very simple experiment, you will see that as you rotate the third, middle polaroid filter, you do start to see light, contrary to my understanding of the theory.
I'm clearly missing something. Can anyone perhaps explain? There was a big argument between my entire class and the teacher over a multiple choice question on the test involving this issue. Her explanations were not satisfactory.
Thanks
