What transition in the hydrogen spectrum would have the same wavelength as the Balmer transition n = 4 to n = 2 in the He⊕ spectrum?
n = 2 to n = 1
We know that
Wave number ¯ν=1λ=[1n21−1n22]Z2×R
Therefore,
¯ν=1λ=(122−142)RZ2=34R
In H spectrum for the same ¯ν=λ as Z=1, n=1, n2=2