Speed of electromagnetic waves in vacuum (c = 1/√(μ₀ε₀))

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c = 1/√(μ₀ε₀)

What each symbol means

SymbolWhat it stands for
cSpeed of EM waves in vacuum (m/s), ≈ 3.00×10⁸
ε₀Permittivity of free space ≈ 8.85×10⁻¹² F/m
μ₀Permeability of free space = 4π×10⁻⁷ H/m

When to use this

Vacuum (or good approximation). Derived from Maxwell's equations; links optical and electromagnetic constants.