This is more of a conceptual question: Where does the equation for the intensity of polarized light come from? I know the standard form is: I=(1/2)(I_0) after the EM wave passes through the first polarizer. Why is that? Why is the intensity exactly half? The polarizer ensures that the only polarizations of light that pass through are those oriented along the same axis as the polarizer. Since the polarization of the light is random, this means any number of the polarizations could be eliminated, right? I am having difficulty understanding how a polarizer automatically blocks out 50% of the light at all times, and how this is true regardless of the angle of the polarizer, since the polarizations are random to begin with.