Alcohol and digital thermometers
Two other thermometers are in common use.
The glass–alcohol thermometer
Built like a mercury thermometer, but with alcohol as the liquid. It measures from −115 °C to 100 °C.
- Ethanol freezes at −115 °C, so it can measure temperatures far below 0 °C.
- It expands more than other liquids, and evenly with temperature.
- Pure ethanol is colourless, so it is dyed to make the column easy to see.
The digital thermometer
It shows the temperature directly as a number. Instead of the expansion of a liquid, it uses an electrical property that depends on temperature, such as resistance.
Figure to be added