Heres a quick question: while conducting an experiment to demonstrate the effect of polarising light waves, i noticed a strange effect. The lecturer used milk and water mixed in a container with a light shining through, allowing the light beam to show. When we looked at the beam from the side, through a polarised lense, the light beam appeared to be coloured, like the surface of oil. I guess this is something to do with defraction, but when i asked the lecturer he did not know how it happened. Can someone explain how this happens.