\( = 0.963 \times {10^{ - 6}}\)
\(\Delta \lambda = {\lambda _2} - {\lambda _1} = 9 \times {10^{ - 6}}\,\,\, \Rightarrow \,\,\,\,\,{\lambda _2} = 9.963 \times {10^{ - 6}}\)
\({\lambda _2} = \frac{b}{{{T_2}}}\,\, \Rightarrow \,\,\,\,{T_2} = \frac{b}{{{\lambda _2}}} = \frac{{2.89 \times {{10}^{ - 3}}}}{{9.963 \times {{10}^{ - 6}}}} = \frac{{2890}}{{9.963}} = 300K\)