Question

Liquid-crystal displays are used in digital watches, calculators, and laptops. Describe the liquid-crystal state, in terms of molecular arrangement, and explain what happens as temperature increases.

Accepted Answer

Liquid-crystal displays are used in many lightweight applications including digital watches, calculators, and laptops because of their low energy consumption. The ability of liquid crystal molecules to transmit light depends on the orientation of the molecules. This can be controlled by the application of a small voltage across a thin film of the material, forming light and dark areas of the display. The arrangement of molecules in liquid crystal phases. (a) The nematic phase. The molecules tend to have the same alignment but their positions are not correlated. (b) The cholesteric phase. The molecules tend to have the same alignment which varies regularly through the medium with a periodicity distance p/ 2. The positions of the molecules are not correlated. (c) smectic A phase. The molecules tend to lie in the planes with no configurational order within the planes and to be oriented perpendicular to the planes.

Thermotropic liquid crystals can be classified into two types: enantiotropic liquid crystals, which can be changed into the liquid crystal state from either lowering the temperature of a liquid or raising of the temperature of a solid, and monotropic liquid crystals, which can only be changed into the liquid crystal state from either an increase in the temperature of a solid or a decrease in the temperature of a liquid, but not both.

Sergey Bylikin, Gary Horner and, Brian Murphy Solutions for Chapter: Materials, Exercise 7: Questions

Sergey Bylikin Chemistry Solutions for Exercise - Sergey Bylikin, Gary Horner and, Brian Murphy Solutions for Chapter: Materials, Exercise 7: Questions

Questions from Sergey Bylikin, Gary Horner and, Brian Murphy Solutions for Chapter: Materials, Exercise 7: Questions with Hints & Solutions

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