Question 18M.3.sl.TZ2.5b
| Date | May 2018 | Marks available | [Maximum mark: 3] | Reference code | 18M.3.sl.TZ2.5b |
| Level | sl | Paper | 3 | Time zone | TZ2 |
| Command term | Discuss | Question number | b | Adapted from | N/A |
Chemical vapour deposition (CVD) produces multi-walled carbon nanotubes (MWCNT) of a more appropriate size for use in liquid crystals than production by arc discharge.
Discuss three properties a substance should have to be suitable for use in liquid crystal displays.
[3]
Any three from:
chemically stable AND does not «chemically» degrade over time
stable over range of temperatures AND to avoid «voltage/random shift» fluctuations ✔
polar AND influenced by an electric field
strong intermolecular forces AND allow molecule to align in specific orientations ✔
rapid switching speed/low viscosity AND change orientation «quickly» when electric field is applied/reversed
Award [1 max] for identifying three correct properties without any discussion or incorrect interpretation of suitability.
Accept “voltage” for “electric field”.
[3 marks]
