Polarizing Filter

Light or other electromagnetic radiation whose electrical component lies parallel to conducting elements in the filter is absorbed, whereas the waves at right angles are not. As the top wave enters the polarizing filter (shown as a pale blue column) it causes electrons to move (shown as a bright light in the column). These electrons absorb energy from the wave and absorb (filter) it. The bottom wave's electrical component is oriented horizontally but since the electrons cannot move horizontally (they are constrained in the column) they cannot absorb energy from this wave and so it passes through unimpeded. Filters can be metal wires or molecules (in huge arrays) oriented in such a way that electrons can only move in one direction. For example, microwaves can be selectively absorbed by a metal grille. This induced movement of electrons in a conductor by an electromagnetic wave is how radio waves are absorbed by an antenna...POLARIZING FILTERS: are used in sunglasses to reduce glare since most reflected light bounces off horizontal surfaces and is thereby polarized horizontally (e.g. reflection from the sea or the surface of a pool). Polarising filters are used in photography for similar reasons. In microscopy they can supply polarised light which is then passed through the object. Changes in the polarization brought about by the object are then made obvious by inspection through a second polarizing filter.