The laboratory thermometer
Two thermometers, the same length. Why can only one read a hot kettle?
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Step 1 of 4
- Two thermometers. Same length.
- Clinical: 35 °C to 42 °C.
- Laboratory: −10 °C to 110 °C.
- Only the wide one reaches a hot kettle.
The rule
Only the laboratory one has a range wide enough for hot water. Range means the lowest and highest numbers on the scale.
A laboratory thermometer is used in science work, not on the body.
It must read icy water and very hot water. So its range is wide: about −10 °C to 110 °C.
The minus sign means colder than zero.
A clinical thermometer stops at about 42 °C. Hot water is above 42 °C. The scale cannot show it.
The range decides what a thermometer can read. Length does not.