| Date | May 2014 | Marks available | 1 | Reference code | 14M.3.hl.TZ2.13 |
| Level | HL | Paper | 3 | Time zone | TZ2 |
| Command term | Describe | Question number | 13 | Adapted from | N/A |
Question
Liquid crystals are an important component in many devices considered essential in modern life, such as smartphones.
Describe the meaning of the term liquid crystal.
[1]
a.
List two properties needed for a substance to be used in a liquid-crystal display.
[2]
b.
Markscheme
fluids that have physical properties dependent on molecular orientation;
a.
chemical stability;
liquid-crystal phase stable over a suitable range of temperatures;
polar (in order to change orientation when an electric field is applied);
rapid switching speed;
b.
Examiners report
There was a generally poor understanding of liquid crystals in Q13 apart from the properties of suitable molecules.
a.
There was a generally poor understanding of liquid crystals in Q13 apart from the properties of suitable molecules.
b.
