Generally, objects are subject to heat expansion and cold contraction. Based on this principle, scientists have been producing and improving thermometers for centuries。
In 1593, galileo designed a gas thermometer:
In 1641, ferdinand ii improved the design of galileo by creating an alcohol thermometer free of atmospheric pressure and a one-time inoculation court。
In 1714, a german physicist, warren hayt, found mercury to be hotter inflating and colder than alcohol and with higher boiling points, producing mercury thermometers with a wider temperature range。
With relatively spectrometric thermometers, a new question arises: how do we set quantitative standards for temperature
Warren hayt mixes water, ice and ammonium chloride with the lowest temperature that can be measured at that time, set at 0°f, thus measuring the temperature of the ice water mixture at 32°f, human body temperature at 96°f and water at a boiling point of 212°f under atmospheric pressure。
This is the first accurately measured temperature measure in history, fahrenheit, in °f。
In 1742, the mercury thermometers made by swedish physicist ursius were set at 0°c and 100°c, respectively, for the ice and boiling points of water, divided into 100 cells at 1°c, which are commonly used in the country。
The mercury thermometer that we use today has evolved from the invention of 300 years ago. It is precise in its measurements, but the temperature is slow and requires three to five minutes in the mouth and armpit。
The mercury is sensitive to temperature changes due to its lower heat content. In the design of the body thermometer, special bending structures have been used to keep the mercury column up and down, allowing for steady reading. Each time, therefore, the mercury column must be thrown back into the glass bubble with great effort。
Inaccessibility with mercury (liquid mercury) itself is highly toxic and recklessly breaks can easily endanger human health, so electronic thermometers and infrared thermostats are now more widely used in the market。
The principle of electron thermometers is, in fact, simple: when they are in full contact with the human body, the internal temperature sensors feel the heat changes and then convert their own variations into the corresponding temperature。
In the case of ntc thermal sensitive resistor temperature, its core element is ntc temperature sensor. This is a semiconductor ceramic made of 2-3 metal oxides that are burned through high temperature exercise。
The higher the temperature, the lower the value of the resistance, using semiconductor electrical resistance features, the greater the temperature, and the corresponding temperature, depending on the value of the resistance。
Electronic thermometers also need to be exposed to humans in order to measure temperature, and thermometers can achieve “airproof temperature measurements”. “system temperature” does not send some mysterious force into the human body. On the contrary, it was the body that fired energy at the thermometer, which was infrared。
In nature, all objects with temperatures above absolute zero (approximately -273. 15°c) are exposed to infrared radiation, the higher the temperature, the greater the infrared radiation. The temperature changes of internal sensors caused by the absorption of infrared by thermostats affect their electrical performance, which is the temperature base for infrared thermometers。
Infrared thermostat guns, for example: it is an internal heat reactor consisting of multiple metal bars, each of which is connected by two different metals。
According to the sebek effect, the temperature difference between the two different conductors causes a voltage difference, the greater the temperature difference, the greater the voltage difference. Depending on temperature and voltage variability, the voltage table measured a difference of 1. 5294 mv at both ends, corresponding to body temperature of 38°c。
When the measurement key is pressed, thermal reactors begin to absorb the energy of human radiation and generate output signals, and the temperature is shown on the liquid crystal screen following the processing of the read-out circuit。
The measurements of the various thermometers are different, the contact thermometers measure the oral, armpit, rectal, and the non-contact thermometer measures the ears, foreheads。
The temperature of heat is different from the place where it was detected. Ears and rectals are closer to the body, and heat rises are more pronounced; lower temperature increases are lower in the armpit than in the body。
As the wrist is at the end of the body, the temperature of the real entity is poor, and therefore it is not recommended that the wrist temperature be measured using a conventional thermostat。
During the autumn winter festival, new coronary virus infections and influenza reached high fever, and if heat symptoms occur, the argon at 38. 2°c or oral temperature at 38. 5°c may be considered for deflammation because of fever. After taking the medication, the heat remained high for more than three days, and those with acute respiratory and suffocation symptoms should go to the hospital。
