Hot and cold are measured using a numerical scale called temperature. Temperature scales are a way for us to tell about the weather, measure safety and comfort, and explain the physical world. Scientists use baselines of choice to create relative measurements, and temperature scales measure thermal intensity or the amount of thermal energy contained in a material or substance (air, pot, sun surface, etc.). I will. There are three commonly used measurement systems: Fahrenheit, Celsius, and Kelvin.
What is temperature?
Temperature is the energy measured by a tool called a thermometer, which is derived from the Greek words “thermos” (high temperature) and “metron” (measurement). Online etymological dictionary..Another definition of temperature is that it is a measure of average Physical energy — Energy of mass during motion — of the molecule of matter Georgia State University
Ancient Greek doctor Hippocrates The journal reportedly reported in 2019 that in 400 BC the human hand could be used to determine the presence of a person’s fever. Nature Public Health Emergency Collection.. However, accurate instruments for measuring human body temperature were not developed until the 16th and 17th centuries.
Fahrenheit: The first precision thermometer
In 1714, Polish-born Dutch physicist, inventor and scientific instrument maker Daniel Gabriel Fahrenheit introduced a mercury-based thermometer. Mercury, Liquid metal expands and contracts based on ambient temperature. When Fahrenheit put mercury in a closed tube marked with a numbered scale, he saw the mercury move up and down when exposed to different temperatures.according to Royal Society In the UK, this was the first known practical and accurate thermometer in the world.
Fahrenheit invented the invention based on the Danish scientist Ole Rømer’s alcohol-based thermometer. Roemer labeled the temperature scale by marking zero at the temperature at which the salt water (salt water) froze and 60 as the point at which the water boiled, said the Institute of Thermodynamics at the Technische Universität München, Germany. The late director, Ulrich Grigull, wrote., At the 1986 conference presentation.. The ice melted at 7.5 degrees Rømer and the human body was registered at 22.5 degrees.
However, Fahrenheit’s thermometer was much more accurate. He used the same freezing and boiling reference points as Roemer’s scale (called “Extream Cold” and “Extream Hott” in his writing), but to divide each marker on the scale into smaller increments. In addition, the scale was roughly quadrupled. On the Fahrenheit scale, Grigal wrote that the four reference points were 0 (at the total freezing temperature of salt water), 30 (normal water freezing point), 90 (body temperature) and 240 (boiling point of water).
Fahrenheit published a treatise in the journal explaining his scale Philosophical transaction That same year, Fahrenheit enrolled in the Royal Society, the National Academy of Sciences in the United Kingdom. Grigal wrote, “His fellowship at the Royal Society brought his thermometer, and thereby his scale, to Britain, and as a result later, especially in North America and the British Empire.” Fahrenheit’s measurement system, sometimes referred to as part of the Imperial system, traveled around the world with the British Empire.
However, very few countries still use Fahrenheit to measure temperature today. The United States and its territory, along with the Bahamas, Palau, Belize, the Cayman Islands, the Federated States of Micronesia, and the Marshall Islands, are sticking to the temperature scale, despite the transition of other parts of the world to the Celsius scale.To online geographic resources world map..
After Fahrenheit died in 1736, the Fahrenheit scale was readjusted to be a little more accurate. The exact freezing points and boiling points of plain water, minus salt, were marked at 32 degrees Fahrenheit and 212 degrees Fahrenheit, respectively. Normal human body temperature was marked at 98.6.
Fahrenheit temperature is often followed by a number with a ℉ or simply represented by an F.
Celsius: More scientific scale
“Anders Celsius should be recognized as the first to conduct and publish a careful experiment aimed at defining a scientifically-based international temperature scale.” Olof Beckman, Solid-state physicist at Uppsala University, Sweden. Celsius is a Swedish astronomer Aurora, Aurora, and also known as Earth magnetic field, And how to determine Brightness of stars, according to National Institute of High Magnetic Fields..
so Suggestion In 1742, Celsius proposed to the Royal Swedish Academy of Sciences a scale based on two fixed points: 0 (boiling point of water) and 100 (freezing point of water). A famous Swedish taxonomist after the death of Celsius in 1744 Carl Linnaeus Proposed to switch fixed points, according to. 0 indicates the freezing point of water and 100 indicates its boiling point. Anders Celsius Heritage JSTOR Daily, digital library. The scale has also been expanded to include negative numbers.
Celsius initially called his scale “Centigrade” in Latin at 100 (“centi”) degrees (“grade”) because there were 100 points between freezing and boiling water. In 1948, the Conference General des Poids et Measures renamed it “Celsius” in honor of Anders Celsius. National Institute of Standards and Technology (NIST)..
The Celsius scale is part of the metric system and is also known as the International System of Units (SI). Temperatures in degrees Celsius can be expressed by adding the symbol ° C, or simply C, after degrees.
The Celsius scale is 100 degrees between boiling and freezing water, while Fahrenheit is 180 degrees. This means that 1 degree Celsius is equal to 1.8 degrees Fahrenheit. At -40 °, the values on both scales are the same: -40 C = -40 F.
Kelvin: An absolute measure for scientists
In 1848, British mathematician and scientist William Thomson (also known as Sir Kelvin) proposed an absolute temperature scale that does not depend on the properties of substances such as ice and the human body. He suggested that the range of temperatures possible in the universe far exceeds those proposed by Celsius and Fahrenheit.According to, the concept of absolute minimum temperature was not new NIST, But Kelvin put the exact number in it: 0 Kelvin is equal to -273.15C.
“Thermodynamic temperature” is different from the temperature based on the freezing point and melting point of the fluid, Julia Scherschligt, a vacuum and pressure measurement expert at the National Institute of Science and Technology, told Live Science.
“The thermodynamic temperature is absolute, not relative to a fixed point. It represents the amount of kinetic energy contained in the particles that make up a mass of matter, and it sways at the ultramicroscopic level,” she said. It was. “When the temperature drops, the particles slow down at some point and stop moving altogether. This is absolute zero, a Kelvin-scale benchmark.”
Absolute zero occurs at -273.15C or -459.67F. Until recently, scientists believed that humans could not reproduce this temperature (which would require additional energy to be added to the system to cool it, that is, the system would be warmer than absolute zero. ).But in 2013, German physicists succeeded in pushing the particles to paradoxical temperatures. Less than absolute zero..
In Kelvin’s view, absolute zero was where the temperature scale started, but for convenience, he used the well-known Celsius-scale markers and spacing as his base. Therefore, on the Kelvin scale, water freezes at 273.15 K (0 C) and boils at 373.15 K, or 100 C.
A single Kelvin is called a unit, not a degree, and corresponds to a single degree on a Celsius scale. The Kelvin scale is mainly used by scientists.
According to a journal article, Kelvin was redefined to be more accurate in 2018 Metrologia, And its definition is now Boltzmann constant.. This constant associates temperature with the kinetic energy inside a substance.
According to the new definition General Assembly on Weights and Measures, Is as follows: “Kelvin, the symbol K, is the SI unit of thermodynamic temperature. Its magnitude is set by fixing the value of the Boltzmann constant exactly equal to 1.380649 × 10-23 … JK-1. I will. [joules per kelvin].. “
Which scale is best for you?
The best measure of temperature depends on the situation, the community with which you share the information. Historically, Americans have used Fahrenheit scales in their daily lives, such as weather and cooking, so it is best to use Fahrenheit measurements in the United States. However, since Celsius is used in most countries, it is advisable to use that scale around the world while communicating internationally. Ultimately, the best scale for casual use depends on convention and what the people around you are using.
But which scale is the most accurate?
“Accuracy isn’t really a feature of scale,” says Scherschligt. Rather, the accuracy of the measurement depends on the increment given by the thermometer used and the skill of the person using it. “Numbers can be measured on any scale with any precision, but only Kelvin is based on physics, which is the most accurate scale.”
Based on the physical properties of any gas, the Kelvin scale can be accurately calibrated anywhere in the universe with the right equipment and universal constants. As a result, scientists often prefer to use the Kelvin scale in their experiments.
From Celsius to Fahrenheit: Multiply by 9, divide by 5, and then add 32.
From Fahrenheit to Celsius: Subtract 32, then multiply by 5, then divide by 9.
From Celsius to Kelvin: Added 273
From Kelvin to Celsius: Draw 273
From Fahrenheit to Kelvin: Subtract 32, multiply by 5, divide by 9, and then add 273.15.
From Kelvin to Fahrenheit: Subtract 273.15, multiply by 1.8, then add 32.
Temperature: Fahrenheit, Celsius, Kelvin | Live Science
Source link Temperature: Fahrenheit, Celsius, Kelvin | Live Science