An electric current
In 1962, RCA researcher Richard Williams generated stripe-patterns in a thin layer of liquid crystal material by the application of a voltage. In 1888, liquid crystals were first discovered in cholesterol extracted from carrots by Austrian botanist and chemist, Friedrich Reinitzer. Each crystal, therefore is either opaque or transparent, forming the lcd television 42 numbers or text that we can read. An electric current passed through the liquid causes the crystals to align in patterns. A simple monochrome LCD display has two sheets of polarizing material with a liquid crystal solution between them. When properly aligned, the liquid crystals allow light to pass through.
