Fahrenheit scale and other temperature scales

Measure the temperature of mankind learned about 400 years ago. But the first instruments, reminiscent of the current thermometers, appeared only in the 10th century. The inventor of the first thermometer was the scientist Gabriel Fahrenheit. Altogether, several different temperature scales were invented in the world, some of them were more popular and still used, others gradually became obsolete.

Temperature scales are systems of temperature values that can be compared with each other. Since the temperature does not belong to values that are directly measurable, its value is associated with a change in the temperature state of a substance (for example, water). On all temperature scales, as a rule, two points are fixed, corresponding to the transition temperatures of the selected thermometric substance in different phases. These are the so-called reference points. Examples of reference points are the point of boiling water, the point of hardening of gold, etc. One of the points is taken as the origin. The interval between them is divided into a number of equal segments, which are single. A unit of temperature is universally accepted one degree.

The most popular and the most widely used in the world temperature scale - the scale of Celsius and Fahrenheit. However, consider in order the existing scales and try to compare them in terms of ease of use and practical use. The most famous scales are five:

1. The Fahrenheit scale was invented by Fahrenheit, a German scientist. In one of the cold winter days of 1709, mercury in the thermometer of the scientist descended to a very low temperature, which he proposed to take as zero on a new scale. Another reference point was the temperature of the human body. The freezing point of water on its scale is + 32 °, and the boiling point + 212 °. The Fahrenheit scale is not particularly thought out and convenient. Previously, it was widely used in English-speaking countries, now - almost exclusively in the US.

2. On the scale of Reaumur, invented by the French scientist Rene de Reaumur in 1731, the lowest reference point is the freezing point of water. The scale is based on the use of alcohol, which expands when heated, for a degree a thousandth part of the volume of alcohol in the reservoir and tube at zero was adopted. Now this scale is out of use.

3. On the Celsius scale (proposed by Swede Anders Celsius in 1742), the temperature of a mixture of ice and water (the temperature at which ice melts) is taken as zero, the other main point is the temperature at which water boils. The interval between them was decided to be divided into 100 parts, and one part is taken for the unit of measurement - degree Celsius. This scale is more rational than the Fahrenheit scale and the Reaumur scale, and is now used universally.

4. The Kelvin scale was invented in 1848 by Lord Kelvin (English scientist W. Thomson). On it, the zero point corresponded to the lowest possible temperature at which the molecules of the substance ceased to move. This value was calculated theoretically in the study of the properties of gases. On a scale of Celsius, this value corresponds to approximately - 273 ° C, i.e., Zero Celsius is equal to 273 K. The unit of measurement for the new scale was one kelvin (originally referred to as the "Kelvin degree").

5. The Rankine scale (named after the Scottish physicist W. Rankin) has the same principle as the Kelvin scale, and the dimension is the same as the Fahrenheit scale. This system is practically not spread.

The temperature values that the Fahrenheit and Celsius scale give us can easily be transferred into each other. When translating "in the mind" (that is, quickly, without using special tables) of Fahrenheit values in degrees Celsius, the original figure should be reduced by 32 units and multiplied by 5/9. Conversely (from the Celsius scale in Fahrenheit) - multiply the original value by 9/5 and add 32. For comparison, the absolute zero Celsius temperature is 273.15 ° F, the Fahrenheit is 459.67 °.