= Wave impedance
{title2=$Z=\sqrt{\mu/\epsilon}$}
{wiki}
For a <plane electromagnetic wave> in a homogeneous, linear, lossless, <isotropic> medium with <permittivity> $\epsilon$ and <magnetic permeability> $\mu$, the wave impedance relates the field amplitudes by $Z=E/H=\sqrt{\mu/\epsilon}$. Its units are ohms. Impedance differences determine the normal-incidence amplitude <Fresnel equations>, $r=(Z_2-Z_1)/(Z_2+Z_1)$ and $t=2Z_2/(Z_2+Z_1)$, with a common tangential electric-field axis.
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