Polaroid film consists of long-chain organic molecules that are aligned so that they only pass light polarized in one direction. What happens to the light that does not pass through? Does it get absorbed, or does it get rotated so that it has the correct polarization? If it gets rotated, then why do we have the effect of blocking light when film at 0º is put in front of film at 90º?
Light with an electric field along the molecules can move electrons back and forth along the molecules. Losses eventually absorb the energy and hence that part of the light
Light with an electric field across the molecules can move electrons significantly, so it goes through unabsorbed.