[j2dac]

Hey guys, have this question for my 1st year exams.

The visible spectrum obtained from a hydrogen discharge tube consists of four
lines at 410,434 nm, 486 nm, and 656 nrn. These lines reflect emissions of
photons by electrons in excited states falling to the quantum level with a principal
quantum number of 2.

Using these data calculate the Bohr constant for the hydrogen atom, and identify
the initial principal quantum number involved in the generation of each of the
given spectral lines.

Cannot figure this one out at all. Any help much appreciated! Thanks.

[tamim83]

First you are going to need the Rydberg formula:

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


I am assuming that the "Bohr Constant" you are trying to find is the Rydberg constant (R_H).  To find it from your data, you will need to plot 1/wavelength vs. 1/n₂².  You can get R_H from the slope or the intercept (intercept is probably simpler.  To figure out which transitions correspond to your data, you will need to think about how the energy level ( :delta:E) is related to the wavelength of the lines you observed.  That will help you match n₂ with each wavelength.  You can also try Googling Hydrogen line spectra if you are stuck, this is a very well known line spectrum so you can compare your data with the literature. 

Hope this helps some. 

[j2dac]

Hey there, thanks for your help.

I googled it and found this:

http://answers.yahoo.com/question/index?qid=20090802073004AAys8oi

Its basically the same question and im sure you use the Rydberg formula. But in the example above he was given the constant and I have to work it out myself given the information I have. Once I know how to get the constant the rest is pretty straight forward (keep subbing in different wavelenghts).

Any more help much appreciated.

Cheers.