Fahrenheit

Fahrenheit

Map showing countries that use Fahrenheit

The Fahrenheit scale is a temperature scale based on one proposed in 1724 by the physicist Daniel Gabriel Fahrenheit. It uses the degree Fahrenheit (symbol: °F) as the unit. The Fahrenheit scale is primarily used in the United States, its territories, and associated states, as well as the Cayman Islands and Liberia.

History

The Fahrenheit scale was developed by Daniel Gabriel Fahrenheit, a Polish-German physicist, engineer, and glass blower. He initially based his scale on three fixed points of temperature. The zero point was determined by placing the thermometer in a mixture of ice, water, and ammonium chloride, a salt. This mixture forms a eutectic system which stabilizes its temperature automatically at 0 °F. The second point, 32 °F, was the freezing point of water, and the third point, 96 °F, was approximately the human body temperature.

Definition and Conversion

The Fahrenheit scale is now usually defined by two fixed points: the temperature at which water freezes into ice is defined as 32 degrees Fahrenheit (°F), and the boiling point of water is defined to be 212 °F, a 180-degree separation as defined at sea level and under standard atmospheric pressure.

The formula to convert from Celsius to Fahrenheit is:

<math>F = \frac{9}{5}C + 32</math>

Conversely, the formula to convert from Fahrenheit to Celsius is:

<math>C = \frac{5}{9}(F - 32)</math>

Usage

Thermometer displaying Celsius and Fahrenheit scales

The Fahrenheit scale is used in the United States and its territories, as well as in the Cayman Islands and Liberia. In most other countries, the Celsius scale is used for most temperature measuring purposes. The Fahrenheit scale is often used in the United States for non-scientific applications, such as weather forecasts, cooking, and body temperature measurement.

Comparison with Celsius

The Celsius scale, also known as the centigrade scale, is used in most of the world. It is based on the freezing point of water at 0 °C and the boiling point of water at 100 °C under standard atmospheric conditions. The Fahrenheit scale, with its 180-degree separation between the freezing and boiling points of water, provides a finer resolution per degree than the Celsius scale.

Related pages

• Celsius
• Kelvin
• Temperature
• Thermometer