The two commonly used devices using polarised light are:
1. Liquid crystal display (L.C.D.)
2. Sun glasses (dark glasses).
1. Liquid crystal display: They are found in many watches and calculators.
Liquid crystals have long molecules whose direction can be controlled by applying electric fields. This is used to modify the light produced by polariser to make its polarisation perpendicular to the axis of an analyser. The analyser cuts these lights and produces dark regions. These dark regions are controlled and are used to form numbers and letters.
2. Sun glasses (dark glasses): These have polaroids. Glare from sunlight reflection from water can be reduced, if the polaroids cut out horizontally polarised light.
