How and what is the measurement of temperature

Monitoring the change in temperature indicators (in other words, thermometry) is required in laboratory or chemical studies, to observe the technology of processes in production or to ensure the safety of products.

It is logical to assume that the technologies used in production are not suitable for household purposes. We will get to know more closely with instruments that allow to carry out measurements in different conditions.

Of course, the most common devices that allow you to measure temperature are thermometers. These include meteorological and laboratory, medical and electrocontact, technical and manometric, special and signaling. The total number of modifications is several dozen.

Methods and devices for determining the temperature

Familiar thermometers for us are just a small part of all the devices or devices that exist today, which are used in a situation where temperature measurement is necessary. The determination of the magnitude of the thermal indices can be carried out by several methods. The principle of operation of each device is a specific parameter of the substance or body. Depending on the range in which the temperature measurement is to be performed, different devices are used.

• Pressure. Its change allows you to monitor temperature fluctuations in the range from -160 degrees to +60. The devices are called pressure gauges.
• Electrical resistance. It is the basic principle of the operation of electrical and semiconductor thermometers for measuring resistance. The difference in readings allows semiconductor devices to measure from -90 degrees to +180. Electrical devices are able to fix from -200 to +500 degrees.
• Thermoelectric effect is the leading property of standardized or specialized thermocouples. Devices of standardized type provide the determination of temperature limits from -50 to +1600 degrees. Specialized devices are designed to work with critical high performance. Their operating range is from +1300 to +2500 degrees.
• Thermal expansion. Used in liquid thermometers, allowing to determine temperatures in the range from -190 to +600.
• Thermal radiation. It is based on the work of pyrometers of various types. Depending on the type of device, the temperature range also varies. Particular attention should be paid to the fact that these devices are suitable only for measuring high positive indications. In color pyrometers, the operating temperature range is 1400 - 2800 degrees. For radiation devices, these figures will be equal to 20 - 3000 degrees. Photovoltaic devices record a temperature of 600-4000, and optical pyrometers will estimate readings in the range of 700-6000 degrees.

Naturally, the question arises as to how the physical properties make it possible to measure air temperature or hot metal. In manometers, the force of gas or liquid pressure is taken as a basis for a certain temperature regime. Pyrometers and thermal imagers allow to estimate the temperature of the surface of an object, perceiving the thermal radiation emanating from it (pyrometers show the data in digital form, the thermal imager provides a "picture" of the object and its temperature). The use of the thermoelectric effect consists in the construction of a thermocouple. By and large, the thermocouple is a closed circuit of two different conductors. A certain temperature effect causes a certain stress. This principle is also used in resistance thermometers.

In general, the methods for measuring temperature can be divided into contact and non-contact methods. The widest example of a contact method is a medical thermometer, a non-contact thermographic camera.