It is important to measure temperatures, but how can it be done? For example, we could take a piece of ice: when the piece of ice starts to melt, its temperature is at least above degrees, and when the resulting puddle starts to boil, its temperature is over degrees. However, this knowledge is not of much use in practice. Over time, various solutions have been invented that measure the temperature a little more accurately.
Liquid thermometer
The first thermometer was introduced at the end of the 16th century and was still based. Later, it was considered reasonable to replace water with mercury, and then they switched to the use of alcohol. Liquid thermometers are based on the phenomenon of thermal expansion, more on that in the next few hours.
Bimetallic thermometer
When visiting a sauna, most of us have seen a thermometer with a metal needle on the wall, which gives an idea of whether the steam is hot enough or whether we have to wait a little longer before going on stage. However, there is no secret ampoule of liquid behind the needle for measurement - it consists of two different metals which, under the influence of temperature, elongate to different degrees and thus bend the needle to the corresponding degree.
Digital thermometer
You can find digital thermometers in many places around you: on your smartphone, car screen, modern refrigerator or kettle and many other places.
Digital thermometers take advantage of the dependence of electrical resistance on temperature, which in turn affects the current through the thermometer's wires. The difference in current is translated into temperature in the thermometer. The thermometer in our set also works on the same principle.