Well, I had to think for a few seconds before I understood what I was observing. I taught physics early in my teaching career and remembered the hours spent trying to demonstrate the concepts of optics to high school students. Polarization of white light is a complex concept to master. But, while reading a webpage on the iPad in the bright sunshine made me thank the writers of the science curriculum.
I would have probably blamed Apple for building a defective device. When I rotated the iPad from the landscape orientation to the portrait orientation, the iPad screen when dark. Hum! Was there something wrong with the motion sensor in the iPad? Was the battery defective? Was the screen leaking? None of the above!
It was basic physics. When two polarized lenses (my Bausch & Lomb shades) and the screen on the iPad are oriented at 90 degrees from each other, light rays are blocked by the lenses.
Sent from an iPad