A thermometer is a device for measuring the temperature of the determined environment: air, soil, water. There are several types of thermometers that differ in their principle of operation: liquid, optical, mechanical, gas, electric, infrared.
Instructions
Step 1
The first thermometer was invented by Galileo. It was airy and showed not the temperature, but its change without numerical values. The modern thermometer was created by Faraday in the 18th century. Initially, he filled the thermometer with alcohol, but later replaced it with mercury. Zero in the Faraday scale was equal to modern 32 degrees, and the temperature of the human body was equal to 96 degrees. In 1742, the physicist Celsius made the points of reference for the temperature of melting ice and boiling water, although initially zero on the scale corresponded to the boiling point of water, but then it took on a modern form.
Step 2
Liquid thermometers work on the principle of changing the initial volume of liquid poured into the thermometer when the ambient temperature changes. Most often, alcohol or mercury is poured into the thermometer flask. The advantages of a mercury thermometer are the high accuracy of temperature measurement, a long period of use, however, the temperature level is set for a long time, mercury in a thermometer is a hazardous material, so the use of a mercury thermometer must be done as carefully as possible.
Optical thermometers record temperature by the level of luminescence, spectrum and other indicators and are most often used in scientific research.
Step 3
Mechanical thermometers operate on the principle of liquid thermometers, only a spiral or a metal strip serves as a sensor.
Electric - work on the principle of changing the resistance level of the conductor when the external temperature changes. Those electrothermometers that have a large range are based on thermocouples - when different metals interact, a contact potential difference arises, which depends on temperature. The electrothermometers have built-in additional functions of memory, backlighting, they are safe and quickly show the result, however, they can give a small error, as a result of which the temperature must be measured several times.
Step 4
An infrared thermometer measures temperature without direct interaction with a person or object, is characterized by measurement accuracy and safety, as well as a high speed of action - half a second. They are hygienic, work quickly (within 2-5 seconds) and help to measure the temperature of children.
