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Kurotan t1_iya833x wrote

Reply to comment by RadBadTad in My thermostat uses the expansion/contraction of a drop mercury to conduct electricity and trigger when to turn off and on. by Iain_MS

What do the digital ones use then? I didn't know they stopped mercury.

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RadBadTad t1_iya8s9i wrote

Modern thermometers use a variety of different methods and sensors to determine the temperature, but some of them include, thermocouples, Resistance Temperature Detectors (RTDs), thermistors, and Solid State sensors. These all use the ideas of voltage, resistance, and current to determine what the ambient temperature is.

The technology is a lot more complex than something like a bimetallic spring and some mercury, but if you're interested there is good reading about it!

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nayhem_jr t1_iya9bjk wrote

Thermocouples measure voltage across a material that is sensitive to temperature, same thing that digital thermometers use. This allows for much more precision and faster response than that old bimetallic switch.

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