Most thermometers usually fall in the category of science laboratory glassware as it made of glass. The laboratory thermometer can be easily identified through its long stem with a silver bulb at its bottom. The silver colour is nothing but mercury which expands as the temperature goes up and contracts as temperature goes down.
Some liquid-in-glass thermometers also contain red alcohol. So, they are also called alcohol or spirit thermometers. However, the liquid content in these thermometers evaporates quickly.Infrared
This type of thermometer comprises a lens that focuses the infrared energy (IR) on to a detector. This detector in turn coverts IR into an electric signal that is further displayed in units of temperature. Its application is best suited for taking temperatures from a distance or measuring it from the surface.Bimetallic Strip
The bimetallic strip thermometer is made of two metals bonded together. It is mainly used to control temperatures and hence, finds a wide application in industries. It is ideal for accurate calculation of high-temperature substances or objects. Basically, it converts temperature into the mechanical displacement.
When the temperature rises, the strip bends towards the metal which has a low-temperature coefficient. On the contrary, when the temperature goes down, the strip bends towards the metal which has a high-temperature coefficient.Thermistor
This thermometer is basically an electronic device. Its name is a blend of thermal and resistor. Its resistance is dependent on temperature. It mainly measures changes in electrical resistance and converts them to changes in temperature.