Skip to content

Boltzmann constant

Оцініть статтю/Rate the article

The Boltzmann constant (k or kB) is a physical constant that defines the relationship between temperature and energy.

Her name is derived from the Austrian physicist Ludwig Boltzmann, who made significant contributions to the study of the statistical nature of heat and entropy.

The Boltzmann constant is denoted as kB and has a value of 1.380649×10-23 J/K. This means that for every Kelvin of temperature, the energy of one particle is equal to 1.380649×10-23 joules.

The universal gas constant is defined as the product of the Boltzmann constant and Avogadro’s number, R = kBNA. The gas constant is more convenient when the number of particles is given in moles.

Calculation of energy for an ideal gas

The formula for calculating the energy (E) for an ideal gas using the Boltzmann constant is as follows:

E = kB ∙ T,


E – average energy of gas particles, k – Boltzmann constant, T – absolute temperature in Kelvin.

Calculation of system entropy

The entropy (S) of a system is given by:

S = kB ​ln W,

where W is the statistical weight of the system state.

The Boltzmann constant is important for understanding physical processes at the molecular level and for understanding the statistical properties of systems. It is a fundamental element in the study of statistical thermodynamics and the motion of particles in gases, liquids, and solids.

Applications of the Boltzmann constant

  1. Thermodynamics and statistical mechanics: It plays a key role in formulating various laws and equations that describe physical systems in thermodynamics and statistical mechanics. For example, it is part of the equation of state for various substances.
  2. Energy distribution: Used to describe the distribution of energy among particles in gases, liquids, and solids at a given temperature. For example, the Maxwell-Boltzmann distribution describes the distribution of molecular speeds in an ideal gas.
  3. Entropy and the second law of thermodynamics: Helps determine the entropy of a system and establish the second law of thermodynamics, which deals with the direction of physical processes.
  4. Signal amplification: In electronics and optics, the Boltzmann constant is used in calculations for amplifiers and other devices.
  5. Energy storage systems: In solar panels and other energy storage systems, it is used to calculate energy conversion efficiency.
  6. Vacuum technology: In vacuum devices, such as electronic vacuum tubes, the Boltzmann constant is used to describe the motion and emission of electrons.
  7. Biophysics: In biophysics and molecular biology, it is used to describe thermodynamic processes within cells and biological systems.
  8. Engineering and materials science: In engineering and materials science, it is used to analyze thermal and energetic properties of materials and processes, such as heat conduction and diffusion.

These are just a few examples of the applications of the Boltzmann constant. Due to its fundamental role in physics and its relevance to various scientific and technological fields, it is a crucial constant in the physical sciences.