Expression for the Balmer series to find the wavelength of the spectral line is as follows:
1 / λ = R [tex] (\frac{1}{2^{2} } - \frac{1}{ n^{2}} )[/tex]
Where, λ is wavelength, R is Rydberg constant, and n is integral value (4 here → Fourth level)
Substitute 1.097 x 10⁷ m⁻¹ for R and 4 for n in the above equation
1 / λ = (1.097 x 10⁷ m⁻¹) [tex] (\frac{1}{2^{2} } - \frac{1}{4^{2} } )[/tex]
= 0.20568 x 10⁷ m⁻¹
λ = 4.86 x 10⁻⁷ m
since 1 m = 10⁹ nm
λ = 486 nm
