Fahrenheit (°F) – The American Temperature Scale
The Fahrenheit scale is widely used in the United States and some Caribbean nations. It was created by German physicist Daniel Gabriel Fahrenheit in 1724 and is based on three fixed points: 32°F (freezing point of water), 212°F (boiling point of water), and 98.6°F (average human body temperature).
History of the Fahrenheit Scale
Fahrenheit’s scale was initially based on a mixture of water, ice, and salt as the lowest calibration point. It was later refined to set 32°F as the freezing point of pure water and 212°F as its boiling point under standard atmospheric pressure.
Usage and Applications
- Weather Forecasting:Used in the U.S., Belize, and some island nations.
- Household Applications:Air conditioning, refrigeration, and oven settings.
- Medical Applications:Body temperature is often measured in Fahrenheit in the U.S.
Conversion Formulas
- To Celsius: (°F - 32) × 5/9
- To Kelvin: (°F - 32) × 5/9 + 273.15
- To Rankine: °F + 459.67
- To Réaumur: (°F - 32) × 4/9
Kelvin (K) – The Absolute Temperature Scale
The Kelvin scale is the absolute thermodynamic temperature scale, used primarily in scientific and engineering applications. It starts at absolute zero (0 K), the point at which all molecular motion ceases.
History of the Kelvin Scale
The Kelvin scale was developed in 1848 by Lord Kelvin (William Thomson). He proposed an absolute temperature scale where absolute zero (-273.15°C) represents the lowest possible temperature.
Usage and Applications
- Physics and Chemistry:Used in gas laws and thermodynamic calculations.
- Astronomy:Measuring temperatures of stars and celestial bodies.
- Scientific Research:Essential for precision temperature measurements.
Conversion Formulas
- To Celsius: K - 273.15
- To Fahrenheit: (K - 273.15) × 9/5 + 32
- To Rankine: K × 9/5
- To Réaumur: (K - 273.15) × 4/5