2η0 = 
, μ0 = 4π10-7 H/m is the permeability of vacuum, and ϵ
0 is the permittivity
of vacuum; ϵ0μ0c2 = 1, so with an approximate c ≈ 3.00 ⋅ 108 m/s, ϵ
0 ≈ (1∕36π)10-9 F/m, and
η0 ≈ 120π ≈ 377 Ω.
2η0 = , μ0 = 4π10-7 H/m is the permeability of vacuum, and ϵ
0 is the permittivity
of vacuum; ϵ0μ0c2 = 1, so with an approximate c ≈ 3.00 ⋅ 108 m/s, ϵ
0 ≈ (1∕36π)10-9 F/m, and
η0 ≈ 120π ≈ 377 Ω.