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The 12 Important Physical Constants

Nucleus and the Number of Protons and Neutrons
Level 2 (without higher mathematics)
Level 2 requires school mathematics. Suitable for pupils.
Updated by Alexander Fufaev on
Table of contents
  1. Speed of light
  2. Elementary charge
  3. Vacuum permeability
  4. Vacuum permittivity
  5. Planck's constant
  6. Gravitational constant
  7. Boltzmann constant
  8. Electron mass
  9. Proton mass
  10. Neutron mass
  11. Avogadro constant
  12. Gas constant

Speed of light

Speed of light tells us how fast light travels in empty space (vacuum).

Value of the speed of light
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Elementary charge

The elementary charge is the smallest, freely existing electric charge in our universe.

Value of the elementary charge
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Vacuum permeability

The vacuum permeability appears in equations that deal with magnetic fields.

Value of the vacuum permeability
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Vacuum permittivity

The vacuum permittivity occurs in equations that deal with electric fields.

Value of the vacuum permittivity
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Planck's constant

The Planck's constant, is a physical constant that appears in equations whenever the equation describes quantum effects.

Value of the Planck constant
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Gravitational constant

The gravitational constant occurs in Newton's law of gravity and Einstein field equations, which describe the interaction between masses.

Value of the gravitational constant
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Boltzmann constant

The Boltzmann constant occurs in equations which describe systems with many particles.

Value of the Boltzmann constant
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Electron mass

The mass of one electron

Electron mass value
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Proton mass

Mass of one proton

Value of the proton mass
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Neutron mass

Mass of one neutron

Value of the proton mass
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Avogadro constant

The Avogadro constant indicates how many particles are present in one mole.

Value of the Avogadro constant
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Gas constant

The (universal) gas constant occurs in thermodynamics - in the description of gases (e.g. air).

Value of the gas constant
Formula anchor