Physics Ontology

One map of physics, three ways in. Drill down on any quantity to see its units, the equations it lives in, and how its values span the universe.

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kBk_B
Fundamental Constants

Boltzmann Constant

Relates average kinetic energy of particles to temperature.

SI unit

joule per kelvin (J/K)

Dimension: [ ML2T−2Θ−1 ][\,M L^2 T^{-2} \Theta^{-1}\,]

Other units

  • joule per kelvin (J/K)

Defined value

Fixed constant from the A-level data sheets.

1.38 × 10-23 J/K

A-level value

Appears in 3 equations

Boltzmann's Entropy Formula
S=kBln⁡WS = k_B \ln W
Ideal Gas Law (Boltzmann form)
pV=NkBTpV = Nk_BT
Molecular Kinetic Energy
12m⟨c2⟩=32kBT\tfrac{1}{2}m\langle c^2\rangle = \tfrac{3}{2}k_BT

Associated scientists

Ludwig Boltzmann