Calculate the wave number and wave length of `H_(alpha)` line in Brackett series of H-emission spectrum

Explanation

For `H_(alpha)` line in Bracket series
`n_1 = 4, n_2 =5`
`bar(?) = R [ (1)/(n_1) - (1)/(n_2) ] = 109677 [ (1)/(4^2) - (1)/(5^2)]=2467.7325 cm^(-1)`
`lambda= (1)/(v) = 4.0 xx 10^(4) cm`