| The visitor,
looking through a polaroid filter, stares down into a cylinder of
syrup with another piece of polaroid beneath it. As the level of
the syrup is changed with a knob in front of the exhibit, various
colors can be observed. Only by rotating the hand-held polaroid
can the visitor see the same color as the level is changing, thus
demonstrating that the plane of polarization is rotated by the syrup.