Photon emission rate from monochromatic power
= Photon emission rate from monochromatic power
{title2=$\dot N=P/(hf)$}
A monochromatic beam of <frequency> $f$ and mean radiated <power> $P$ carries mean <photon> rate $\dot N=P/(hf)$. It follows by dividing <energy> per unit time by <energy> per <photon>. A broadband source instead requires integrating spectral <power> divided by the frequency-dependent <photon energy>; electrical input <power> must first be converted to radiated <power>.