Thermology in Physics
Thermology in Physics

Thermology is the branch of physics that studies phenomena related to heat, temperature, changes in physical state, the study of gases, thermal expansion, etc. Thermology can be divided into three parts: thermometry, responsible for studying temperature and thermometric scales, such as Celsius, Fahrenheit, and Kelvin; calorimetry, an area that studies heat exchange between bodies; and thermodynamics, studying the relationships between heat, energy, and work, through the Laws of Thermodynamics.


Thermometry is the area of ​​physics that studies temperature and thermometric or Thermology scales. In the following figure, it is possible to observe the melting and boiling points of water on the main thermometric scales: Celsius, Kelvin and Fahrenheit .

Celsius, Kelvin and Fahrenheit .
Celsius, Kelvin and Fahrenheit .

Temperature is one of the fundamental physical quantities , which can be understood as the macroscopic effect of the agitation of the atoms that make up matter. Temperature is measured through the use of a thermometer .

In addition to the scales mentioned above, there are many others based on different characteristics of matter. Among all these scales, only one is considered a thermodynamic scale : the Kelvin scale , which is directly based on the agitation of atoms.

Below, you can check the formula used to convert a certain temperature represented on one thermometric scale to another:



Calorimetry is the branch of thermology that studies heat exchange. Heat is a form of energy, which, according to the Laws of Thermodynamics, flows spontaneously between bodies of different temperatures, from the hottest body to the coldest body, until these bodies are at the same temperature.

As it is a form of energy, heat is measured in joules, according to the International System of Units ( SI ), however, it is common for heat to be defined in calories. In the study of calorimetry, we say that there are two distinct forms of heat: sensible heat and latent heat, let’s understand each of them.

  • Sensible heat

Sensible heat is that which is transferred between bodies of different temperatures, exclusively promoting temperature change . The formula used to calculate sensible heat is shown below, please note:

The formula presented, known as the fundamental equation of calorimetry, can also be written in terms of the heat capacity of the body:

  • latent heat

Latent heat is the energy exchanged between bodies of different temperatures, responsible for exclusively promoting changes in physical state . When some pure substance reaches the state transition temperature (solid-liquid, liquid-gas, for example), it will receive or give up sensible heat until its physical state has changed, in the meantime, its temperature will remain constant .

The formula used to calculate latent heat is shown below, please note:


Thermodynamics is the area of ​​physics that studies the relationships between heat, energy and work . the Thermodynamics permeates several areas of knowledge and is fundamental for understanding physical systems of various scales: from cells to galaxies function in accordance with the Laws of Thermodynamics.

  • Zeroth law of thermodynamics

The Zeroth Law of Thermodynamics, also known as the Law of Thermal Equilibrium, concerns the condition under which heat exchanges occur. When different bodies have different temperatures, heat must flow from the hotter bodies towards the bodies with a lower temperature, until the temperature between them becomes equal. To learn more about this law, visit: Zeroth Law of Thermodynamics

  • The first law of thermodynamics

The First Law of Thermodynamics is known as the Law of Conservation of Energy . According to this law, all energy in the form of heat that is added to a system can be transformed into work , or can be absorbed by the system itself, resulting in an increase in the system’s internal energy .

Below, you can check the formula described by the First Law of Thermodynamics:

  • Second Law of Thermodynamics

The Second Law of Thermodynamics, known as the Law of Entropy, concerns the disorder of thermodynamic systems. The formula used to calculate the entropy change is shown below, check it out :

  • Third Law of Thermodynamics

The Third Law of Thermodynamics is known as the law of absolute zero . According to this law, this temperature, corresponding to 0 K or -273.15 ºC, is unreachable . To learn more about this area of ​​Thermology, visit: Thermodynamics .

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