## Rydberg’s formula

H-Atom ($E_{n}=-\frac{hR}{n^{2}}$)

Faisal Alshamaa - 1L
Posts: 31
Joined: Fri Apr 06, 2018 11:01 am

### Rydberg’s formula

Hello,
We did this question in class. Calculate the frequency of light emitted by a hydrogen atom when an electron makes a transition from fourth to second principal quantum level. I noticed that using Rydberg's formula gives us the same answer as the answer we got using professor Lavelle's way, which was to find the energy difference first and then plug that into v=E/h to find the frequency.
I'm confused as to how that gave us the same answer since different constants were involved? Is there a difference between when we should use Rydberg's formula versus the way the professor showed us?
Thank you!

Mei Blundell_1J
Posts: 32
Joined: Fri Apr 06, 2018 11:01 am
Been upvoted: 1 time

### Re: Rydberg’s formula

What Professor Lavelle did was the exact same thing as the Rydberg equation. He took the difference in energies at the two levels. If you look at the Rydberg equation, you'll see that that's what it does. The constants look different just because they're rearranged, but they are the same. I recommend doing what Lavelle did symbolically, without plugging in the numbers. Then compare what you get the Rydberg, you'll see that they're the same.