The thermometer is a widely used instrument for measuring the temperature of solids, liquids, and gases. There are many areas that make use of the thermometer as a measuring instrument, either in the laboratory, the kitchen or in the industries. Among the best known is the field of medicine, where it is used to measure body temperature and thus determine if the patient has a feverish picture.
According to the use that will be given to the thermometer, it will present a scale and a unit of measure. The most common units of temperature measurement are: Celsius, Fahrenheit, and Kelvin . Being the Celsius scale the most used in the world.
History of the thermometer
In 1592 the Italian scientist Galileo Galilei invented the thermoscope , an instrument that is considered the predecessor of the thermometer. This consisted of a glass tube with a sphere at the top. The lower part was exposed and had to be submerged in a substance of alcohol and water. The liquid rose or fell through the tube as the temperature changes were experienced.
Between 1611 and 1613, a numerical scale is added to the thermoscope. Said incorporation is attributed to Francesco Sagredo and Santorio Santorio . Considered the creators of the thermometer.
Types of Thermometers
Today there is a wide variety of thermometers, each designed for different uses. To next, some of them:
- Mercury thermometer: it is perhaps the best known and most widely used, since they are used to measure body temperature. It was created in 1714 by the physicist Gabriel Fahrenheit. It consists of a sealed glass tube that has mercury inside, which, as the temperature increases, expands throughout the tube. The temperature can be seen on the graduated scale, either in degrees Celsius (° C) and Fahrenheit (° F).
- Pyrometer: this thermometer is used to accurately measure high temperatures. It is capable of capturing the temperature without the need to be in contact with the object or surface.
- Bimetallic Foil Thermometer: as its name indicates, this thermometer is made up of two metallic foils, each with a different coefficient of expansion. These sheets perform circular movements, which contract with heat and expand with cold. These movements are captured by a transmitter and sent to a needle which reveals the temperature.
- Gas Thermometer: this type of thermometer is highly complex and accurate, therefore its use has been limited to repair and calibrate other thermometers.
- Resistance thermometer: the operation of this thermometer consists of a material that is capable of changing its electrical resistance as the temperature varies, thus giving the result of the measurement.
- Thermal torque: this thermometer consists of two metals which are joined at one end. The other ends must be placed on the object to be measured, the junction point of the threads will heat up, resulting in the temperature.
- Digital thermometer: they are very easy to use and much safer than mercury thermometers. It consists of a system that is capable of perceiving energy through a resistance, it travels through an electrical circuit that is the one who transforms that energy in the measurement of temperature.
Examples of thermometers
- Infrared ear thermometers
- Pacifier thermometers
- Plastic strip thermometer
- Pill thermometer
- Kitchen thermometers