## Chapter 1: Exercise 15

$c=\lambda v$

Alma Cruz 1A
Posts: 21
Joined: Fri Jun 23, 2017 11:40 am

### Chapter 1: Exercise 15

For exercise 1.15, I understand that we have to use Rydberg's equation to solve for n2. However, when I compared my answers to the one in the solutions manual, I noticed that frequency is not included.

My question is, why do we not include frequency(lambda) when using Rydberg's equation when solving for n2?

Haifa 1B
Posts: 4
Joined: Sat Feb 04, 2017 3:00 am

### Re: Chapter 1: Exercise 15

Lambda is the wavelength (102.6 nm), it was used to calculate the frequency, which was then used in the Rydberg equation

Isaiah Little 1A 14B
Posts: 50
Joined: Fri Sep 29, 2017 7:05 am

### Re: Chapter 1: Exercise 15

Wavelength is given instead of frequency most likely because the creators of the book wished for you to do an extra step to make the problems more complex. However, you can find the frequency from wavelength using c=lambda*nu, where lambda is the wavelength and nu is the frequency. Just rearrange the equation so that it's with respect to nu and solve for nu.

Jennie Fox 1D
Posts: 66
Joined: Sat Jul 22, 2017 3:01 am

### Re: Chapter 1: Exercise 15

In order to solve the problem, you do use the wavelength. In order to solve for n2, you must first find the frequency (v) so that you can plug the frequency into Rydberg's equation. To find the frequency, you use the equation v=c/lambda. Then you use plug this frequency into Rydberg's equation, v=R((1/(n1)^2)-(1/(n2)^2)). You should get n2=3 for your answer.

Hope that helps!

Joshua Hughes 1L
Posts: 81
Joined: Sat Jul 22, 2017 3:01 am
Been upvoted: 3 times

### Re: Chapter 1: Exercise 15

So I did the problem and got the final answer as 3. What I'm confused about is N1 and N2, I know one is the final and the other is initial energy level but which one is N1 and which is N2. I wrote part of the equation as ((1/Nf)-(1/Ni)) or is it supposed to be the other way around with the initial minus the final energy level? One of the reasons I was thinking that N1 was the final and N2 was the initial was because of the wording of the problem said there was an emission of energy with a wavelength of 102.6 nm meaning that the electron should be dropping to a lower energy level and that the initial one should be the higher energy level. But then the solutions manual said the "The TRANSITION is n1= 1 TO n2= 3" which confused me because if there is an emission of energy why is the electron going to a higher energy level. Also, I thought Layman series are specifically transitions from a higher energy level to the first energy level so the wording of the solutions manual is just confusing me.I'm probably just looking at this wrong/missing something really simple that's going to make me facepalm later.