Answer:
λ = 397 nm
Step-by-step explanation:
given,
Rydberg wavelength equation for Balmer series
![(1)/(\lambda)=R((1)/(n_f^2)-(1)/(n_i^2))](https://img.qammunity.org/2021/formulas/physics/college/ivzqdo72agwg15qaz61u92gem4e9dd12in.png)
R is the Rydberg constant, R = 1.097 x 10⁷ m⁻¹
n_i = initial energy level
n_f = final energy level
where as for Balmer series n_f = 2
n_i = 7
![(1)/(\lambda)=(1.097* 10^7)((1)/(2^2)-(1)/(7^2))](https://img.qammunity.org/2021/formulas/physics/college/252bsa5m3rjop4q76odmabdr7zxfksgkrl.png)
![(1)/(\lambda)=(1.097* 10^7)((1)/(2^2)-(1)/(7^2))](https://img.qammunity.org/2021/formulas/physics/college/252bsa5m3rjop4q76odmabdr7zxfksgkrl.png)
![(1)/(\lambda)=2.5186* 10^6](https://img.qammunity.org/2021/formulas/physics/college/ab26quo722i0it2zxp4v6dszy0fg0hrbzy.png)
![\lambda = 3.97* 10^(-7)](https://img.qammunity.org/2021/formulas/physics/college/eiwkx5afi5atu1hjknn8rm2891rc7tiwry.png)
Hence, the wavelength is equal to λ = 397 nm