Rydeberg's Equation Help

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apurva-3E
Posts: 135
Joined: Wed Sep 30, 2020 9:59 pm

Rydeberg's Equation Help

Postby apurva-3E » Wed Oct 28, 2020 4:44 pm

So I know there are two formulas and one of them is v = R(1/n^2 - 1/n^2) . I understand that when an electron absorbs a photon, it moves to a higher energy level and the energy is positive. Why do I calculate a negative value using this equation when moving to a higher energy level?

For example, lets say an electron is excited from n = 2 to n = 6.
R * (1/36 - 1/4) gives me a negative value but shouldn't it be positive since it is absorbing the photon?

I know this is kind of confusing to understand what I'm saying but hopefully you can help! :)

Nathan Lao 2I
Posts: 83
Joined: Wed Sep 30, 2020 9:40 pm
Been upvoted: 1 time

Re: Rydeberg's Equation Help

Postby Nathan Lao 2I » Wed Oct 28, 2020 5:32 pm

I think you switched the n1 and n2 values in the equation. The final level(n2) is 6 and the initial level(n1) is 2 for this electron transition. This is because the electron is going from n=2 to n=6. This should help you get a positive value.

Jason_Glass_2L
Posts: 91
Joined: Wed Sep 30, 2020 9:43 pm

Re: Rydeberg's Equation Help

Postby Jason_Glass_2L » Wed Oct 28, 2020 5:59 pm

apurva-1H wrote:So I know there are two formulas and one of them is v = R(1/n^2 - 1/n^2) . I understand that when an electron absorbs a photon, it moves to a higher energy level and the energy is positive. Why do I calculate a negative value using this equation when moving to a higher energy level?

For example, lets say an electron is excited from n = 2 to n = 6.
R * (1/36 - 1/4) gives me a negative value but shouldn't it be positive since it is absorbing the photon?

I know this is kind of confusing to understand what I'm saying but hopefully you can help! :)


A good thing to remember is that the first n is always going to be a lower energy level than the second n because frequency has to be positive in Rydberg's equation.

Audrey Han 3L
Posts: 81
Joined: Wed Sep 30, 2020 9:38 pm

Re: Rydeberg's Equation Help

Postby Audrey Han 3L » Wed Oct 28, 2020 6:39 pm

It might help your understanding if you try to derive the equation! Personally, I like how it allows me to manipulate the sign in the beginning since when I use deltaE=Ef-Ei, I can make deltaE positive or negative depending on the problem.


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