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**1. Homework Statement**

What values of n are involved in the transition that gives the rise to the emission of a 388-nm photon from hydrogen gas?

**2. Homework Equations**

n=?

wavelength = 388nm=3.88x10^-7 m

R=1.097x10^7 m^-1

E= hc/ wavelength

**3. The Attempt at a Solution**

E= hc/ wavelength=(6.63x10^-34)(3.00x10^8)/ (3.88x10^-7) = 5.13x10^-19 J = 3.206 eV

En = -13.6eV / n^2

n = - square root of (13.6/En) = -square root of (13.6/3.206) = - square root of 4.24 = -2.06

n = 2 <- 1st excited state

the answer is n=8 to n= 2.

How would I know that it began from n=8 ?? Maybe there's an equation that I missed..