\(\left( {\frac{{d\lambda }}{{dt}}} \right) = \frac{{P\lambda }}{{hc}}\,\,\,\)
\(\frac{{{{\left( {\frac{{dn}}{{dt}}} \right)}_{uv}}}}{{{{\left( {\frac{{dn}}{{dt}}} \right)}_{5R}}}} = \frac{{{\lambda _{UV}}}}{{{\lambda _{5R}}}} = \frac{4}{7} = 0.57\)