Science Thermometers

Thermometers

  By: Elisa Gan

             In science, we have been learning about thermometers.There are three different scales that could be used on a thermometer. They are: Kelvin, Celsius, and Fahrenheit. All of these scales have different number readings for the same temperature. An example would be for water's freezing point. In Celsius, it would be 0 degrees Celsius. In Fahrenheit, 32 degrees, and in Kelvin it would be 273 degrees.There are three main types of thermometers: liquid-in-glass, gas, and metal thermometers.

              On a liquid-in-glass thermometer, there are 5 main parts. They are: the scale, stem, bore, the liquid inside, and the bulb. The scale is the numbers on the thermometer that tells you the temperature. The stem is the outside of the thermometer. The bore is the inside part of the thermometer that holds he liquid inside of it. The place where the liquid is stored is called the bulb and is located at the bottom of the thermometer. The liquid inside of a thermometer could be mercury or alcohol. In schools, it is more likely that the liquid would be alcohol because it is less poisonous than mercury. Alcohol is also a lot cheaper than it is to have mercury in a thermometer. Some advantages of having mercury are that it doesn't stick to the glass as often as alcohol does. It can also be used for a lot higher temperatures than alcohol. Another difference between the two is their colour. Mercury is silver and alcohol could be blue or red depending on the colouring that has been used. This thermometer is the most commonly used thermometer.

                 Another thermometer was the gas thermometer. The gas inside this thermometer expands and contracts very easily making it very precise. The advantage between this thermometer and the liquid-in-glass thermometer, is that it can reach temperatures a lot higher than the liquid-in-glass thermometer. The most commonly used gases in this thermometer are air, nitrogen, and hydrogen.

                The other thermometer was the metal thermometer. Most of these thermometers are made out of a bimetallic strip. This strip is made by join together two very thin strips of two different types of metals. In these thermometers, the mos commonly used metals are brass and steel. These two metals are used because their expansion and contraction rates are really different. Brass is the metal that would expand and contract a lot quicker than the steel. When the coil in the thermometer is heated, it would open up, and when it is cooled, it would contract and tighten up.