• Question: How does a thermometer work?

    Asked by DPJ to Adrian, Gaia, Jim, Scott, Vicky on 10 Mar 2016.
    • Photo: Adrian Buzatu

      Adrian Buzatu answered on 10 Mar 2016:

      It contains a tiny amount of liquid mercury that changes its volume with temperature. That different heights are read on a scale. There are also thermometers working with electricity.

    • Photo: Gaia Andreoletti

      Gaia Andreoletti answered on 10 Mar 2016:

      Hi DPJ,

      Old thermometers had a liquid inside. This liquid is sometimes colored alcohol. The alcohol gets bigger when heated and smaller when cooled. Inside the glass tube of a thermometer, the liquid has no place to go but up when the temperature is hot and down when the temperature is cold

    • Photo: Scott Lawrie

      Scott Lawrie answered on 10 Mar 2016:

      Most materials get bigger when they get hot. Some are really nice and repeatable so you can tell very accurately how hot it is by measuring the size of that material. Did you know that big metal bridges and train-tracks get longer on hot days, so they need gaps every so often to prevent them breaking?

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