[kaystrife]

Hi everyone I came across with this problem today:

Calculate the energy (in eV) for the second highest-energy transition of the Pfund series.

To my understanding, the second highest-energy transition of the Pfund series is the energy transition from n=∞-1 to n=5, and I used the equation 1/λ = R_H(1/n^2 - 1/m^2).

But since ∞-1 ~ ∞ and the answer obtained will be equal to the energy transition from n=∞ to n=5

I'm not good at maths and I'm not sure if there's way to distinguish ∞-1 from ∞, or did I misunderstand the question?

Please help, thank you 

P.S. Sorry for my poor English

[Corribus]

That is kind of a bizarre question, but I agree with your answer. The transitions reach a convergence limit at high energy (the energy level density approaches infinity), so there is no functional energy difference between the highest energy transition (which equals the ionization potential) and the second highest energy transition, which is infinitesimally close to the highest energy transition.

I guess the question is supposed to be tricky.

http://en.wikipedia.org/wiki/Hydrogen_spectral_series