**Introduction to Types of Temperature Scales **

We use Temperature scales are very much useful in our daily lives. Furthermore, we can use a temperature scale to know the hotness of an oven. Moreover, a doctor uses a temperature scale in his thermometer to measure the fever in his patient.

The importance of temperature scale is clear from these two examples. Moreover, the temperature scale enables us to know the hotness or coldness of a material as it quantifies the hotness or coldness. Also, the thermometer is based on the application of a temperature scale.

**Celcius Temperature Scales**

First of all, Andrew Celcius ( A Swedish astronomer) developed the Celcius scale. Furthermore, the representation of the temperature is as ^{0}C or degrees centigrade or degrees Celcius. For example, 120^{0 }C means 120-degrees centigrade or 120 degrees Celcius.

Moreover, in the Celcius scale, the freezing temperature of the water is as 0-degree Celcius. Also, this 0-degree Celcius is as a lower fixed point. Furthermore, the boiling temperature of the water is as 100-degree Celcius.

This 100-degree Celcius is as an upper fixed point. The division of the interval between the upper and lower fixed point takes place into 100 equal parts.

Thus Celcius scale has 100 equal parts between 0 degrees Celcius and 100 degrees Celcius. Each of these parts represents a particular temperature.

The Celcius scale is very much in use all around the world for commercial and scientific measurements of temperature. In India also, the Celcius scale is in wide use. In the USA , instead of the Celcius scale, the use of Fahrenheit scale takes place.

**Fahrenheit Temperature Scales**

Daniel Gabriel developed the Fahrenheit scale in 1744 when he was inventing alcohol and mercury thermometers. The representation of the temperature is as ^{0}F or degrees Fahrenheit. For example, 120^{0 }K means 120 kelvin. In the Fahrenheit scale, the freezing temperature of the water is as 32^{0 }F and it is the lower point.

The boiling temperature of the water is taken as 212^{0 }F and is fixed as the upper point. The division of the Fahrenheit scale takes place into 180 equal parts. The wide use of the Fahrenheit scale takes place in the USA. If we compare the Fahrenheit scale and Celcius scale, we get the following relation: 100^{0 }C = 212^{0 }F and 0^{0 }C = 32^{0}

**Kelvin Scale Physics**

Lord Kelvin developed the Kelvin scale in 1848. The derivation of the Kelvin scale is from the Celcius scale only. Kelvin scale does not use degrees and its writing form is as Kelvin or K.

Celcius scale and Fahrenheit scale used degrees in their notation. The basis of the Kelvin scale is on the concept of Absolute Zero. Absolute Zero is the temperature at which everything including air freezes.

At absolute zero, the molecules of any substance have the lowest energy. Experts take absolute zero as a lower fixed point for the Kelvin scale and its writing takes place as 0 kelvin.

The boiling point of water is taken as 373 kelvin. Therefore, 373 K is taken as the upper fixed point. Kelvin scale is widely used as SI ( standard international ) unit for the measurement of temperature.

If we compare the Celcius scale and Kelvin scale, we get the following relation: 273^{0 }C= 373 K and -273^{0 } = 0 K.** **

**Formulas for the Temperature Scales**

In order to convert temperature represented in one scale to another scale, we can use the following formulas:

- Degree Centigrade to Degree Fahrenheit: Temperature in degrees Fahrenheit = ( Temperature in Degree centigrade X 1.8 ) + 32.
- Degree Fahrenheit to Degree Centigrade : Temperature in degrees Centigrade =( Temperature in Degree Fahrenheit – 32) / 18.
- Kelvin to Degree Centigrade : Temperature in degrees Centigrade = (Temperature in Kelvin – 273.15 )
- Degree Centigrade to Kelvin : Temperature in Kelvin = (Temperature in degrees Centigrade + 273.15 )
- Degree Fahrenheit to kelvin : Temperature in Kelvin = 5/9 X (Temperature in degrees Fahrenheit – 32) + 273.15.
- Kelvin to Degree Fahrenheit: Temperature in degrees Fahrenheit = 1.8 X ( K – 273.15) + 32

**Solved Question for You**

**Q: Why Kelvin is taken as an SI unit of temperature and not celsius?**

**Ans:** Kelvin scale is based on the concept of absolute zero. Absolute zero is the temperature at which all the materials freeze. Celsius scale is based on the boiling and freezing point of water, under specific atmospheric conditions.

The boiling point of water may vary when the atmospheric pressure changes. This is the reason why celsius is not the SI unit for measuring temperature.