Editorial Feature

What is a Thermometer?

A number of people have contributed to the development of the thermometer - Cornelis Drebbel, Robert Fludd, Galileo Galilei and Santorio Santorio. The word thermometer was derived from two Greek word fragments – ‘thermo’ meaning ‘heat’ and ‘meter’ meaning ‘to measure’.

Thermometers are instruments used for measuring temperature or temperature gradient by using many different principles. They are capable of measuring the temperature of solids, liquids, or gases. The thermometer is made up of two key elements: the temperature sensor and a medium that allows for the conversion of physical change into a numerical reading for the end-user.

Image Credits: Photos.com.

Types of Thermometers

The following are some of the common types of thermometers:

  • Alcohol thermometer
  • Mercury-in-glass thermometer
  • Beckmann differential thermometer
  • Bi-metal mechanical thermometer
  • Coulomb blockade thermometer
  • Galileo thermometer
  • Infrared thermometer
  • Liquid crystal thermometer
  • Quartz thermometer
  • Rectal thermometry
  • Resistance thermometer
  • Reversing thermometer
  • Silicon band-gap temperature sensor
  • Thermistor
  • Thermocouple.

Working Principle

The measurement of temperature is performed by the thermometer by using mercury, which - when heated - expands, and contracts in response to a fall in temperature. This causes the length of the liquid column to be longer or shorter depending on the temperature.

Today, thermometers are calibrated in standard temperature units such as Celsius (used in Canada/UK), Fahrenheit (used in USA), or Kelvin (used mainly by scientists).


Thermometers are required for numerous purposes from the household to the industrial sectors. In the kitchen, temperature of foods can be measured. Likewise in the refrigerator, it helps to maintain a set temperature. In a factory, the thermometer in the furnace enables turning on and off of the furnace. It is therefore important to choose the right type of thermometer to suit the intended application.

Given below is a list of other crucial thermometer applications:

  • In engine or bearing monitoring
  • Air conditioning systems
  • Transport and automotive spot checks
  • Food preparation surfaces
  • For detecting hidden problems
  • For surveying buildings to spot moisture and leaks
  • For identifying energy loss and poor insulation, electrical faults, and plumbing issues
  • In laboratories and storage rooms.


Tell Us What You Think

Do you have a review, update or anything you would like to add to this article?

Leave your feedback
Your comment type

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.