Notes:

1. This definition implies the exact relation ${{K_{\rm{cd}}}} = {{683}}\ {{\rm{cd}}\:{\rm{sr}}\:{\rm{kg}}^{-1}\:{\rm{m}}^{-2}\:{\rm{s}}^{3}}$ for monochromatic radiation of frequency ${\nu} = {540 \times 10^{12}}\ {{\rm{Hz}}}$. Inverting this relation gives an exact expression for the candela in terms of the defining constants ${K_{\rm{cd}}}$, ${h}$ and $\Delta\nu_{\rm{Cs}}$: $$1\;{\rm{cd}} = \left(\frac{{K_{\rm{cd}}}}{{683}}\right)\ {\rm{kg}}\ {\rm{m}}^2\ {\rm{s}}^{-3}\ {\rm{sr}}^{-1}$$ which is equal to $$1\;{\rm{cd}} = \frac{1}{(6.626\:070\:15 \times 10^{-34})\:({9\:192\:631\:770})^{2}\:{683}} (\Delta\nu_{\rm{Cs}})^{2}\:{h}\:{K_{\rm{cd}}} \approx 2.614\:8305 \times 10^{10} (\Delta\nu_{\rm{Cs}})^{2}\:{h}\:{K_{\rm{cd}}}$$.
2. The effect of this definition is that one candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency ${540 \times 10^{12}}\ {{\rm{Hz}}}$ and has a radiant intensity in that direction of ${1/{{683}}}\ {\rm{W}\ \rm{sr}^{-1}}$ The definition of the steradian is given below Table 4.