Light reflected from a glass pane is partly (and in a particular case fully) polarized. Our task is to
obtain such a setting of an angle of light incidence to a glass pane and such a setting of a
polarizer so that a reflected light did not go through a polarizer! Search of such setting requires
a lot of patience and attention. When you succeed, you can assume that light reflected from a
glass pane is fully polarized. An angle of incidence at which reflected light is fully polarized is a
result of the experiment.