1. The problem statement, all variables and given/known data Approximately 4% of the intensity of light is reﬂected at a glass-air boundary. Classically one expects roughly 8% of light to be reﬂected from a thin glass plate (4% at the front and back boundary). Outline brieﬂy what quantum theory predicts for a single photon instead of a light beam, in particular, say how this diﬀers from the classical prediction. 2. The attempt at a solution If light shines on an imperfectly transparent sheet of glass it may happen that 96% of light transfers through the glass, this makes sense if light were a wave, as the wave splits and a smaller wave is reflected back. But light is considered as a steam of particles so the glass has a 96% chance of being transmitted and 4% chance of being reflected. The behaviour of the photon is totally random and unpredictable. It is defined as a wave function. A particle when not being measured or located takes the form of a field of probable locations some being more probable or as likely than others. Is that right?