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Degree Fahrenheit

Degree Fahrenheit

The Fahrenheit degree (° F) is a temperature unit proposed by Gabriel Fahrenheit in 1724.

On the Fahrenheit scale, the melting point of water is 32 degrees of temperature, and the boiling point is 212 degrees. A difference of 1.8 degrees Fahrenheit equals that of 1 degree Celsius. Fahrenheit established the zero temperature (0 ° F), the freezing point of a 50% mixture of salt (ammonium chloride) and ice, and as 96 ° F, he took the temperature of the blood (he used that of the horses ). The figure 96 may seem an odd measure, but in principle the scale contained only twelve equal subdivisions, he himself divided each division into eight more, finally obtaining 96 divisions on its scale.

The conversion formulas to Celsius and Kelvin degrees are:

° F = ° C⋅ (9/5) + 32
° C = (° F -32) ⋅ 5/9
° F = K ⋅ (9/5) -459.67
K = (° F + 459.67) ⋅ 5/9

Use of the Fahrenheit scale

This scale is currently confined to the Anglo-Saxon countries, especially to the United States. The other Anglo-Saxon countries, however, are adapting to the Celsius degrees, since since the 1960s, some governments have carried out policies with a tendency towards the adoption of the International System and the use of the Fahrenheit for temperature measurement was displaced . However, in the United States, the Fahrenheit is used by the population for non-scientific uses and for very rigid industries, such as oil.

The Fahrenheit scale, has absolute zero located at -459.67 ° F, to facilitate its scientific use, the Rankine scale was created. The Rankine scale takes 0 from the Fahrenheit scale to absolute zero, similar to what happens between Kelvin and Celsius.

History of the Fahrenheit scale

Daniel Fahrenheit

Daniel Fahrenheit is the physicist responsible for creating the scale that bears his name to measure temperature.

Daniel Gabriel Fahrenheit (Gdansk, May 24, 1686 - The Hague, County of Holland, September 16, 1736) was a German physicist, engineer and glassblower who is known for the invention of the alcohol thermometer (1709), the mercury thermometer (1714) and the development of a scale for the measurement of temperatures that we will explain next.

Beginnings of the invention of the Fahrenheit scale

Fahrenheit himself wrote in 1724 that, in his scale, the 0º corresponded to the temperature of a mixture of ice, salt and water, while 100º was the body temperature of the human being. We can see that the temperature in these two environments is not totally accurate, so it is considered that the Fahrenheit scale is quite arbitrary.

It is not known exactly how it was designed since the German physicist and engineer kept his formulas secret.

Fahrenheit was based on the Rømer scale, proposed by the Danish astronomer Ole Christensen Rømer in 1701. According to this scale, 0º was the freezing temperature of the brine and 60º the boiling point of the water. The problem was that other important points, such as body temperature, became fractional numbers, which to Fahrenheit seemed unsophisticated. Fahrenheit decided to adjust the Rømer scale so that the water would freeze at 8º and the body temperature of the human being would be 24º.

The first Fahrenheit thermometers used this scale, but at some point decided to multiply the number of divisions by 4, giving rise to the current Fahrenheit scale where the freezing point is 32 ° F and the body temperature is 96 ° F. It is not known for sure why he did this, but the fact is that he agrees that a Fahrenheit degree increases the volume of mercury by exactly 0.01%.

Inventor of the thermometer

Daniel Gabriel Fahrenheit is also responsible for the invention of the mercury thermometer. Fahrenheit knew that mercury was a better measuring liquid than the alcohol used in other thermometers, since it boiled at a much higher temperature (357 ºC versus 78 ºC). His thermometers became the most reliable of the time, and for those achievements he was formally accepted into the Royal Society of London.

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Last review: November 7, 2017