Impedance Of Free Space

In physics, Impedance of free space also known as the characteristic impedance of free space is a physical constant denoted by Z0 relates the magnitude of the magnetic field and the electric field of electromagnetic radiation travelling through free space. It is expressed as the square root of the ratio of permeability of free space to the permittivity of free space.

Exact Value of Impedance

The exact value of Impedance of free space is universally accepted and defined value is-

Impedance of free space Z0 = 119.9169832 πΩ = 376.73031346177… Ω.


The Impedance of free space can be mathematically written as –

\(Z_{0}=\frac{E}{H}=\sqrt{\frac{\mu _{0}}{\varepsilon _{0}}}=\mu _{0}c_{0}=\frac{1}{\varepsilon _{0}c_{0}}\)


  • μ0 is the permeability of free space.
  • ε0  is the permittivity of free space.
  • C0 is the speed of light in free space.
  • H is the magnetic field strength.
  • E is the electric field strength.

Z0 some time also referred as the admittance of free space.

Hope you have understood the Impedance of free space or the characteristic impedance of free space along with value and units and the formula.

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