Cross Poles
The other day I wanted my class to look at my computer screen through a polariser but I could only find one bit of Polaroid. With 18 in the class it takes a long time to pass around the precious bit of plastic so I decided to buy some more and I found some on Ebay. To be honest I am a little disappointed by the size of the Polaroid sheets but you only need enough to cover one eye so they should be OK.
I’ve just remembered what happened to the other sheets. Last summer I tried to make myself a pair of polarising sun glasses. I must’ve got the angles wrong because when I got to the river I couldn’t see any fish. I was wanting my student to see the coloured patterns you get when a piece of clear plastic is placed between crossed polarisers. The plastic bag that the sheets came in worked nicely. I noticed that when the sheet was rotated through 90° the colours change then come back again as you can see on the video. I’m not sure why that is.