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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μ0\mu_0
Fundamental Constants

Vacuum Permeability

Permeability of free space; appears in electromagnetism and SI definitions.

SI unit

henry per metre (H/m)

Dimension: [ MLT−2I−2 ][\,M L T^{-2} I^{-2}\,]

Other units

  • henry per metre (H/m)

Defined value

Fixed constant from the A-level data sheets.

1.26 × 10-6 H/m

A-level value (4π × 10⁻⁷)