Everybody has used a thermometer in one way or another. Be it to determine the weather outside, or to measure the temperature of the body, everyone of us used thermometers at least once in our lives. But what do you know about them? Do you know where or how thermometers are used? Today, we will tell you all about the different types of thermometer and their uses.
What is thermometer?
First of all, let’s define the word ‘thermometer’. Its name comes from merging two Latin terms together: ‘thermo’, which means heat, and ‘meter’, which means a measuring device. When you combine them, you get ‘thermometer’, which is literally a device to measure heat. In other words, thermometer is a tool that allows you to measure the temperature of anything.
Did you know?
To express the temperature in numeric format, most thermometers use the degrees Celsius (°C) or Fahrenheit (°F). In science, you can also find thermometers with the Kelvin (K) scale, which is tied to the temperature of the absolute zero.
How do you use thermometers? Find out below.
Uses of thermometer As we established, the main use of thermometer is to measure temperature. You can measure the temperature of many things to get useful information about your surroundings and yourself. For example, if you measure the temperature of the air outside, you will know how to dress appropriately. If you measure your body temperature, you will find out whether you have a fever or not.
But wait, there is more: Thermometers are used in science and production to measure the temperatures of different metals, liquids, gases and other materials. You can also use a thermometer to figure out the temperature of your food while cooking.
There are various types of thermometers, depending on the sphere of use and the mechanism involved in determining the temperature.We will tell you about most common types of thermometers. Additionally, you will be able to learn about different types of thermometer used to determine body temperature.
Types of thermometer
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You can find different methods of thermometer classification. We decided to go with the principle of operation as a defining characteristic. Therefore, there are 6 kinds of thermometer based on how they work.
This type is also known as a pressure-filled or vapour-pressure thermometer. It determines the temperature based on the change of pressure in gas or liquid. Manometric thermometers can be filled with gas (nitrogen), condensation (alcohol, chloromethane, diethyl), liquid (metals with low melting points, silicon liquids, metaxylene) or mercury.
This type is the oldest and most common kind of thermometer. It is used almost everywhere, and its principle of operation is very simple.
This thermometer consists of a glass bulb and stem filled with a working liquid (alcohol or mercury) and an inert gas. When the temperature changes, the liquid expands or shrinks. When paired with a temperature scale, it is possible to use this occurrence to determine the temperature.
A gas thermometer determines the temperature based on the difference in pressure or volume of gas it is filled with. There are constant pressure and constant volume gas thermometers. The latter is more commonly used. Gas thermometer can be filled with any gas, but the most popular option is hydrogen. This type works best with very low temperatures.
Bimetal (bimetallic) thermometer
This is a mechanic thermometer that works with a bimetal strip. Bimetal means that it is made of two metals. The strip is sensitive to the change in temperature, and it causes mechanical displacement, which is used to determine the temperature. These thermometers are perfect for higher temperatures, as they become less sensitive and accurate at lower temperatures. They can be found in many household appliances like stoves.
Digital or electronic thermometers are one of the most recent developments in the thermometer field. Instead of using liquids or gases paired with a temperature scale, they have a digital screen, which can show you the readings in mere seconds. A digital thermometer has a thermistor that reacts to the change in temperature and projects the result on the thermometer screen.
All of the thermometers we mentioned above require contact to determine temperature. Infrared thermometer uses thermal radiation that objects emit to infer temperature. This means that they can tell temperature from a distance. Some call them ‘temperature guns’ as most of the infrared thermometers are handheld and look like miniature guns.
All of the types we mentioned in this section can be used for different purposes: industry, science, cooking, medical purposes. However, we want to talk a little bit more about the clinical thermometers, as they are probably the most common ones that everyone has to deal with.
Medicine is one of the spheres where determining a patient’s temperature is one of the most important things in figuring out a problem and dealing with it. There are six most common clinical thermometers used in hospitals and homes.
➣ Mercury-filled thermometers. One of the oldest types, mercury-filled thermometers are slowly disappearing from most countries. In addition to not being the most accurate, they might be very dangerous if broken. The mercury inside is toxic to people and the environment.
➣ Alcohol-filled thermometers. A safer alternative to the previous type, these thermometers use coloured alcohol that expands when exposed to increased temperature. However, both of these liquid-filled thermometers require some time to show the temperature. If you want more immediate results, consider one of the following options.
➣ Temperature strips. Although temperature strips are not thermometers per se, they are often used in hospitals as a way of quickly determining a patient’s temperature. These strips contain liquid crystals that react to heat by changing colour. Each colour corresponds with a certain body temperature. This type is fast, but it is not the most reliable.
➣ Infrared thermometers. This type is mostly used to determine the person’s temperature through their ear. However, some infrared thermometers determine the temperature near a person's forehead. It works almost instantly; in a few seconds, you can get a precise temperature reading on a small screen.
➣ Digital thermometers. Digital thermometers are quickly replacing all of the old liquid-in-glass versions. They are fast, accurate and convenient. With the help of oral, rectal and armpit digital thermometers, you can get your results in mere moments.
➣ Basal thermometers. Even though they are only a form of digital thermometer, they are still different. This type is meant for women that are trying to get pregnant. It allows women to track ovulation, as it is accurate to 1/100 fraction of a degree. Some of the versions also have a function that lets you see the previous readings, which makes it easier to take note of the changes.
That is it for our classification of different thermometers. There are many other classifications, but we tried to keep it concise and informative. We hope that you have learned something new about the thing you pay little attention to.