 Radiation spectrum

The distribution of emitted or received electromagnetic power, radiative flux or specific intensity across frequency or wavelength. The spectral quantity and interval convention must be specified: $F_{\nu }$ and $F_{\lambda }$ differ by the change-of-variable factor, while $\nu F_{\nu }$ gives energy flux per logarithmic frequency interval. This physical spectrum is distinct from the spectrum of a linear operator or a spectrum in topology.