8.4 Polarization of Light by the Method of Reflection
In 1808, Malus discovered that polarized light is obtained when ordinary light is reflected by a plane sheet of glass. If the reflected light is viewed through a polaroid which is slowly rotated about the line of vision, the light is practically extinguished at a certain angle orientation of the polaroid. The most suitable angle of incidence "" is about for glass for which the reflected ray becomes plane polarized, as illustrated by ray diagram in Fig. (8.6). This proves that the light reflected by the glass is practically plane polarized. Light reflected from the surface of a table becomes darker when viewed through a rotated polaroid, showing that it is partially plane polarized.