PhysicalConstantsConventional

Conventional value of ε₀ (pre-2019): derived exactly from μ₀ and c

ε₀ = 1/(μ₀c²) = 1/(4π × 10⁻⁷ × (299792458)²) ≈ 8.8541878176... × 10⁻¹² F/m (exact with exact μ₀)

Conventional value of μ₀ (pre-2019): exactly 4π × 10⁻⁷ H/m

This was the exact defined value before the 2019 SI redefinition. Use this if you need exact rational arithmetic or are working with pre-2019 calculations.