Calculat ethe wave length and frequency associated with the spectral line having longest wave lengthin the Pfund series of hyrogen spectra.

Explanation

In the case of Pfusnd series, spectral line with longest wavelength is obtained when electronic transition occurs from `n_2=6` to `n_(1)=5`. Thus,
`overline(v)=(1)/(lamda)=109678((1)/(5^(2))-(1)/(6^(2)))=1340.5`
`therefore lamda=7.4xx10^(-4)cm`
`v=(c)/(lamda)=(3xx10^(10))/(7.4xx10^(-4))=4.05xx10^(13)s^(-1)`
`=4.05xx10^(13)Hz`