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### Clarification on ENERGY LEVEL concept

Posted: Wed Oct 12, 2016 7:07 am
Hi,
I have noticed that from the book(page 7 in chapter 1), atomic spectra calculation done by Rydberg could be written using the formula: v(frequency)=R[1/n1^2-1/n2^2].

However, in the course reader, we have done the example on page 48 using a different formula:
Change of E=E(final)-E(initial)
E(n)= -hR/n^2
v=E/h

Both equation will give me the frequency correctly, but if the question asks for quantum level(denoted by n), the answer came out different.
What is the difference between these two formulas?
Are we able to use both ways to solve for frequency, and only use page 48 in course reader to solve for quantum level?

Is it kind of confusing?
Thanks,

### Re: Clarification on ENERGY LEVEL concept

Posted: Wed Oct 12, 2016 2:53 pm
When looking for the quantum level it's important to realize that if the level is decreasing then you are going to have a negative energy change. That's why when you use
the change in energy =
-hr/n^2final - (- hr/n^2initial) you have to make sure your change in energy is consistent with whether n is increasing (positive change) or n is decreasing (-).

### Re: Clarification on ENERGY LEVEL concept

Posted: Wed Oct 12, 2016 5:03 pm
So for the quiz, the equation we memorize doesn't matter as long as we can distinguish if the energy is decresing or increasing and apply correctly, right?

### Re: Clarification on ENERGY LEVEL concept

Posted: Wed Oct 12, 2016 7:10 pm
I don't think that the equation you memorize and use in quizzes matters, as long as you use it correctly! They should give you the same answer if applied correctly. So, just be sure to know how to apply the equation you wish to use, and you should be fine for the quiz.