Temperature Unit Conversion Formula
| Celcius to Fahrenheit | [°F] = [°C] × 9/5 + 32 |
| Celcius to Kelvin | [K] = [°C] + 273.15 |
| Celcius to Rankine | [°R] = [°C] × 9/5 + 491.67 |
| Celcius to Reaumur | [°r] = [°C] × 4/5 |
| Fahrenheit to Celcius | [°C] = ([°F] − 32) × 5/9 |
| Fahrenheit to Kelvin | [K] = ([°F] + 459.67) × 5/9 |
| Fahrenheit to Rankine | [°R] = [°F] + 459.67 |
| Fahrenheit to Reaumur | [°r] = ([°F] – 32) x 4/9 |
| Kelvin to Celcius | [°C] = [K] − 273.15 |
| Kelvin to Fahrenheit | [°F] = [K] × 9/5 − 459.67 |
| Kelvin to Rankine | [°R] = [K] × 9/5 |
| Kelvin to Reaumur | [°r] = ([K] – 273.15) x 4/5 |
| Rankine to Celcius | [°C] = [°R] × 5/9 − 273.15 |
| Rankine to Fahrenheit | [°F] = [°R] − 459.67 |
| Rankine to Kelvin | [K] = [°R] × 5/9 |
| Rankine to Reaumur | [°r] = ([°R] – 491.67) x 4/9 |
| Reaumur to Celcius | [°C] = [°r] × 5/4 |
| Reaumur to Fahrenheit | [°F] = [°r] x 9/4 + 32 |
| Reaumur to Kelvin | [K] = [°r] × 5/4 + 273.15 |
| Reaumur to Rankine | [°R] = [°r] x 9/4 + 491.67 |
What is Temperature ?
Qualitatively, we can describe the temperature of an object as determining the warm or cold sensation that is felt upon contact with it.
It is easy to show that when two objects of the same material are placed together (physicists say when they are in thermal contact), the object with the higher temperature cools while the colder object gets warmer until a point is reached after which there is no more change. . happens, and according to our senses, they feel the same way.
When the thermal change stops, we say that the two objects (physicists define it more strictly as systems) are in thermal equilibrium. Then we can determine the system temperature by saying that the temperature is the same quantity for the two systems when they are both in thermal equilibrium.
If we further experiment with more than two systems, we find that many systems can be brought into thermal equilibrium with one another; thermal equilibrium does not depend on the type of object used. To be more precise, If two systems are separated in thermal equilibrium with a third, then they must also be in thermal equilibrium with each other, and they all have the same temperature regardless of the type of system.
The statements in italics, which are called the zero law of thermodynamics, can be restated as follows:
- If three or more systems are in thermal contact with each other and all are in equilibrium together, then the two systems taken separately are in equilibrium with each other. (quote from T.J. Quinn’s temperature monograph)
Now one of the three systems can be a calibrated instrument for measuring temperature – namely a thermometer. When the calibrated thermometer is put into thermal contact with the system and reaches thermal equilibrium, we then have a quantitative measure of the system temperature.
For example, a clinical mercury thermometer in a glass is placed under the patient’s tongue and allowed to reach thermal equilibrium in the patient’s mouth – we then look at how much silvery mercury has expanded on the stem and read the thermometer scale to determine the patient’s temperature.
What is thermometer ?
A thermometer is a device that measures the temperature of a system quantitatively. The easiest way to do this is to find a substance whose properties change regularly with temperature. The most direct of the ‘usual’ methods are linear:
t (x) = ax + b, where t is the temperature of the substance and changes with changes in the x properties of the substance.
The constants a and b depend on the material used and can be evaluated by assigning two temperature points to the scale, such as 32 ° for the freezing point of water and 212 ° for the boiling point.
For example, element mercury is a liquid in the temperature range of -38.9 ° C to 356.7 ° C (we will discuss the Celsius ° C scale later). As a liquid, mercury expands as it gets warmer, its expansion rate is linear and can be accurately calibrated.
The glass mercury thermometer illustrated in the image above contains a light bulb filled with mercury that is allowed to develop into capillaries. The rate of development is calibrated on a glass scale
Temperature Measurement
Different physical properties directly depend on temperature and because they are used for temperature measurement, such as, for example:
- dependence of expansion on temperature
- changes in electrical resistance with temperature
- voltage generation is temperature dependent
- temperature dependent frequency fluctuation
- changes in the radiation wavelength of an object, depending on its temperature