Thermodynamic Scales


The study of the relationship between heat, temperature, work, and energy is known as thermodynamics. The scales that are used to measure these thermodynamics are termed thermodynamic scales. The two temperature scales normally employed for measurement purposes are the Celsius (oC) scale and Fahrenheit (oF) scale. 

Types of temperature scales

There are two types of temperature scales which are:

  • Empirical scale

The scales which measures the physical parameters ,usually a simple linear, functional relationship 

  • Thermodynamic scale 

The scales based on thermodynamics law and have absolute measurements 

Further that thermodynamic scales for temperature measured in different units describes below.

Kelvin scale 

A thermodynamic scale used to measure temperature whose unit of measurement is kelvin are known as kelvin scale. In SI unit it is the base unit of temperature. Symbolically it is represented as ( K ).

By convention the zero on kelvin scale also known as absolute zero is equal to -273.16 oC. At this temperature their is no movement of particles. 

The boiling temperature of water is (373.16K) and melting point of water is (273.16K) these temperatures are taken as reference in kelvin scale, when these two temperatures are divided by 100 equal parts then these are termed as kelvin scale not a degree scale. For the conversion of kelvin scale into Celsius scale, the formula is

K = oC + 273

Celsius scale 

Also known as the centigrade scale , it is the temperature scale based on 0oC  freezing point of water and 100oC boiling point of water. Both temperatures are determined at atmospheric pressure. The interval between these freezing and boiling points is divided into 100 equal parts called degree Celsius or degree centigrade. This scale was first introduced by Swedish physicist , astronomer and engineer Andres Celsius. A change of one degree Celsius is equivalent to the change of one kelvin.

Fahrenheit scale 

In 1724 a German physicist and engineer Daniel Gabriel Fahrenheit proposed a temperature scale known as Fahrenheit scale. 

On Fahrenheit scale two temperatures are taken as reference one is boiling point of water which corresponds to 212 F 0 and other is melting point of water which corresponds to 32 F 0 .

The interval of these two temperatures are divided into 180 parts known as degree Fahrenheit scale. 

Rankine scale 

In 1859 a Scottish engineer and physicist William J. M. Rankine (1820 – 1872) proposed a temperature scale known as Rankine scale. 

Like the Kelvin temperature scale, the Rankin scale is absolute ( zero-degree is the absolute zero temperature. Unlike Kelvin, which took the Celsius size of the interval (100 ° between the melting point of ice and the boiling point of water at normal atmospheric pressure), Rankine took the magnitude of the degree Fahrenheit (180 ° between the melting point of ice and boiling point of water at normal atmospheric pressure).

Other scales such as Douglas scale , , Reaumur scale , Romer scale, Delisle scale, Leiden scale, Newton scale are disused scale. Their uses can be eradicated due to invention in scientific world. 

Energy measurement scale 

In order to express the quantity of energy sources human being used different units of measurement basis on their sources. Comparing sources of energy with different units of measurement of physical quantities us quiet difficult but not impossible. 

The official measurement unit for energy is joule. 

Among the most common units of energy kilo-watt/hour is also a unit of energy that is especially used for electrical energy. 

Measurement scale for heat 

The most common units measuring heat includes the BTU (British thermal units) and kilogram calories (kg-Cal) and especially ton of oil equivalent. 

Ton of oil equivalent is most common at international level because it is connected with the most important and widely used fuels 

So,  by using these different scales we can measures the thermodynamic temperature , work and energy.


Concepts Berg

What are the 3 main scales of temperature?

The three main temperature scales are

  1. Celsius
  2. Kelvin
  3. Fahrenheit

What are the advantages of thermodynamic temperature scale

What is the thermodynamic temperature scale in the English system?

The Celsius scale is most commonly used for temperature scales in most English countries.

What are the 5 types of temperature scales?

The 5 types of temperature scales are:

  1. Kelvin
  2. Celsius
  3. Fahrenheit
  4. Rankine
  5. Douglas

Why is there a need for a thermodynamic temperature scale

What is absolute thermodynamic temperature scale?

The absolute thermodynamic temperature scale is which 0 of temperature is equal to absolute zero. The kelvin and Rankine scales absolute temperature scales.

What is the purpose of developing absolute thermodynamic temperature scale


What is the relationship between the three temperature scales

The three temperature scales kelvin, degree centigrade, and Fahrenheit has following relation

oC = K + 273

oF = 9/5 oC + 32

By using above formulae, three temperature scales ate convert into one another.


Temperature scale by britannica

Thermodynamic scales by eniscuola

Thermodynamic properties and scales by solar-energy-technology

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