Question

the wavelength of second line of the paschen series for hydrogen

Answer 1

Okay first lets start with the Rydberg formula for Hydgrogen spectra:\[\frac{ 1 }{ \lambda }=R \left( \frac{ 1 }{ n _{1}^{2} }-\frac{ 1 }{ n _{2}^{2} } \right)\]where λ is the wavelength of the spectral line; R is the Rydberg constant; and n1 and n2 are energy levels where n2>n1.

The different hydrogen spectral line series each have a different n1. For the Paschen series, n1=3, and n2=4,5,6,7,8.....∞. So if you want to calculate the wavelength of the the second spectral line, n1=3 as stated, but what do you think n2 equals? Note I've given a strong hint in my definition of n2.