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4 LIQUIDS AND SOLIDS eLearn.Punjab

(ii) Liquid crystals are used to find the point of potential failure in electrical circuits. Room
thermometers also contain liquid crystals with a suitable temperature range. As the temperature
changes, figures show up in different colours.
(iii) Liquid crystalline substances are used to locate the veins, arteries, infections and tumors.
The reason is that these parts of the body are warmer than the surrounding tissues. Specialists can
use the techniques of skin thermography to detect blockages in veins and arteries. When a layer
of liquid crystal is painted on the surface of the breast, a tumor shows up as a hot area which is
coloured blue. This technique has been successful in the early diagnosis of breast cancer.
(iv) Liquid crystals are used in the display of electrical devices such as digital watches, calculators
and laptop computers. These devices operate due to the fact that temperature, pressure and
electro-magnetic fields easily affect the weak bonds, which hold molecules together in liquid
crystals.
(v) In chromatographic separations, liquid crystals are used as solvents.
(vi) Oscillographic and TV displays also use liquid crystal screens.

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