Strange behaviour of a television set
A couple of days ago, I was walking past my tv set (which uses an old-fashioned crt) and I saw an illuminated triangular shape on the screen, about the lenth of a finger joint. It was made up of vertical lines in a vivid fluorescent green. The set was switched off at the wall, not on standby.
I unplugged the set, but the shape remained in place. I plugged it in again and switched it on. It displayed a normal picture. When I switched it off again, the shape was gone. I have not seen it again.
I know that crt screens contain coloured phosphors that react to the electron beam but what could have caused this long-term phosphorescence? Is my set haunted?