The Challenge: Make a Thermometer
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How are modern
The most common kind
of thermometer consists of a liquid, such as alcohol or mercury,
in a very thin, hollow glass tube. It works because of the fact that liquids
expand more than solids as their temperatures increase. If both the liquid
and glass expanded equally, the whole thermometer would simply increase
in size. Instead, what actually happens is that the liquid expands more
than the glass and moves up the capillary, registering a change in temperature.
Thermometers are usually calibrated with a certain range of temperatures
in mind. For example, a clinical thermometer used to measure human body
temperature might only have measurements ranging from 32°C to 42°C (90-107°F).
The Rough Science glass thermometer