Throughout the world, there are many different units of measuring temperature. The three most important ones are Fahrenheit (F), Kelvin (K), and Celsius (C). Key Facts & Summary
Whether we use Celsius, Fahrenheit, or Kelvin in our efforts to measure temperatures, is not that important. However, if we find ourselves in certain regions where the temperature measurement is different, knowing the differences between the three most used systems may come in handy. All three are correct ways of noting temperatures and they all can be derived from one another through formulas since they are related to each other. But are these units of measurement any different from each other except for their different values? Yes and no, and here is a bit about every one of them. CelsiusAlso called centigrade, is a scale based on 0 degrees for the freezing point of water and 100 degrees for the boiling point of water. This system was invented in 1742 by the Swedish astronomer Anders Celsius. Some still call it the centigrade scale because of the 100-degree interval between the defined points. The Celsius scale is part of the metric system and is used to measure the temperature in many countries. It is the easiest scale to use and though it is used throughout the world, there is one exception, the United States. In the US, the Fahrenheit scale prevails but the Celsius scale is also not accepted in certain places where Kelvin is used. The normal human body temperature is 32°C, and the absolute zero value is set at -273.15°C, on this scale. To convert Celsius to Fahrenheit is pretty simple: °C to °F: Multiply by 9, then divide by 5 and then add 32. Example: How to convert 28°C to Fahrenheit (°F).First step: 28°C × 9/5 = 252/5 = 50.4. Second step: 50.4 + 32 = 82°F. The Celsius scale and the Fahrenheit scale coincides at -40°, which is the same for both. When it comes to converting Celsius degrees into Kelvins, the formula is even simpler. 0 degrees Celsius is equal to 273.15 Kelvins. The basic formula is °C + 273.15 = K. Kelvin to Celsius: Add 273. Example: How to convert 28°C to Kelvin (K). First step: 28°C + 273.15 = 301.15 K FahrenheitThis temperature scale is based on 32 degrees for the freezing point of water, and 212 degrees for the boiling point. The interval between the two points is divided into 180 equal parts. The German physicist Daniel Gabriel Fahrenheit devised this scale in 1724. The average human body temperature is 98.6°F, while the absolute zero is -459.67°F on this scale. The Fahrenheit scale is accepted and is used in the United States and some of its territories. To convert Fahrenheit degrees into Celsius, here is the formula: °F to °C: Subtract 32, then multiply by 5, then divide by 9. The basic formula is (°F – 32) × 5/9 = °C or precisely (F – 32)/1.8. Example: How to convert 98.6° Fahrenheit into Celsius (°C)First step: 98.6°F – 32 = 66.6. Second step: 66.6 × 5/9 = 333/9 = 37°C. When it comes to converting Fahrenheit degrees into Kelvins, the formula is even simpler. Subtract 32, multiply by 5, divide by 9, then add 273.15. (°F − 32) × 5/9 + 273.15 = K. Example: How to convert 98.6° Fahrenheit into Kelvin (K) (98.6°F − 32) × 5/9 + 273.15 = 310.15K KelvinThis temperature scale is named after the British mathematician and physicist William Thomson Kelvin, who proposed it in 1848. It is an absolute temperature scale, having an absolute zero below which temperatures do not exist. Each unit on this scale is called a Kelvin rather than a degree. For this reason, just the K, not the degree symbol °, is used when reporting temperatures in Kelvin. There are no negative numbers on the Kelvin scale, as the lowest number is 0 K. Absolute zero cannot technically be achieved. It is the temperature at which molecules would stop moving – it is thus “infinitely cold.” The freezing point of water in Kelvin is 273.15K and 373.15K the boiling point. The idea for the Kelvin scale was sparked by a discovery in the 1800s of a relationship between the volume and the temperature of a gas. When it comes to the other scales, Kelvins and Celsius become equal at high temperatures as the difference of 273.15 between them gets lost in the noise. To convert Kelvin into Celsius, the formula is quite simple. K to °C: Add 273 K − 273.15 = °C Example: How to convert 35°C into Kelvin (K) 35°C + 273.15 = 308.15K To convert Kelvin into Fahrenheit, the formula is: (K − 273.15) × 9/5 + 32 = °F. Subtract 273.15, multiply by 1.8, then add 32. Example: How to convert 75°F into Kelvin (K) (75°F − 32) × 5/9 + 273.15 = 297.039K Fun Facts
Conversion Formulas
TriviaMercury thermometersNot too long ago, thermometers had mercury inside the glass. If the temperature got hotter, the mercury expanded and moved up through the narrow tube. We could see what the temperature was by reading it off the scale of numbers on the tube. However, mercury is very toxic and it was soon replaced with different liquids. The concept remains the same regardless, as the temperature goes up, the liquid expands and rises, and when the temperature goes down, the liquid shrinks and drops down the tube. Did you know?
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