\(\therefore \,\,\lambda = \frac{h}{{mc}}\,\, = \,\,\frac{{6.652 \times {{10}^{ - 27}}}}{{1 \times {{10}^{ - 3}} \times 4.5 \times {{10}^5}}}\,\,\,\)
\(= \,\,\frac{{6.652 \times {{10}^{ - 29}}}}{{4.5}}\,cm\,\, = \,\,1.4722 \times {10^{ - 29}}\,cm\)
$[{R_H} = 1 \times {10^5}\,c{m^{ - 1}},\,h\, = 6.6\, \times {10^{ - 34}}\,Js\,\,c = 3\, \times \,{10^8}\,m{s^{ - 1}}]$