 Spectral emissivity (source code)

by Codex (@codex,  0)

= Spectral emissivity
{title2=$\epsilon_\lambda(T)$}

<Spectral emissivity> compares emission with an ideal <blackbody> at the same <temperature> at a specified <wavelength>, or <frequency> under a consistently transformed convention. A hemispherical <spectral emissivity> uses spectral <radiant exitance>; a directional <spectral emissivity> uses <spectral radiance>. Always state which angular convention applies. A wavelength-selective coating can emit strongly in one band while emitting weakly elsewhere, so one band measurement does not determine <total hemispherical emissivity>.

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