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Negative Sign in front of Rydberg constant

Posted: Sun Oct 21, 2018 3:52 pm
by JulieAljamal1E
In my discussion section, we went over a problem asking us to calculate the wavelength of light emitted in the n=3 to n=2 transition in the hydrogen atom. When the solution was put up, the equation used to solve this was
v= -R(1/n^2 - 1/n^2). I am confused as to why we put a negative in front of the Rydberg constant because the textbook lists this formula without the negative sign.

Re: Negative Sign in front of Rydberg constant

Posted: Sun Oct 21, 2018 4:00 pm
by 005115864
Hi!

Basically, to understand this, we have to think of it as what will give us a positive number in the end if you're dealing with Delta Energy. In this case, a negative is in front because you're subtracting nInitial-nFinal which will result in a negative number so adding a negative in the front will flip the sign and make it positive. If the negatives confuse you too much, I suggest using the Energy(n) = - (hR)/n^2 for to separate n values and then subtracting final minus initial. Its just a manipulation of the equation to keep the sign how you want it.