## calculating the frequency of light

Monica Soliman 3F
Posts: 109
Joined: Wed Sep 30, 2020 9:57 pm

### calculating the frequency of light

In the lecture today, we were given an example problem where we had to calculate the frequency of light emitted. where did the -1/16 come from? and the -1/4? I have attached my notes below for the full equation. Thank you.
Attachments

Isis_DW_3G
Posts: 124
Joined: Wed Sep 30, 2020 10:04 pm

### Re: calculating the frequency of light

Hey monica,
The 1/16 and the 1/4 are what you get when you square "n". In this case we want to find DeltaE by subtracting the Final E (n=2) from the Initial E (n=4) so we have to plug the n's into the equation En=-hR/n^2. 4^2 is 16 and 2^2 is 4- Dr. Lavelle just wrote out the fractions so we could see it more clearly.
Hope this helps!

Lucy Wang 2J
Posts: 101
Joined: Wed Sep 30, 2020 10:09 pm
Been upvoted: 2 times

### Re: calculating the frequency of light

The -1/16 is denoting the energy for when the n=4. In the equation, E = (hR)/n^2, so when n=4, it would be (-1/16)*hR. The -1/4 is showing when n=2.

emmaferry2D
Posts: 139
Joined: Wed Sep 30, 2020 9:47 pm

### Re: calculating the frequency of light

In the equation used ( E=h(R/n^2) n is squared. Dr Lavelle simplified this part of the equation and put -1/16 and -1/4 instead of 1/4^2 and 1/2^2

Tiao Tan 3C
Posts: 109
Joined: Wed Sep 30, 2020 9:59 pm

### Re: calculating the frequency of light

We are using the empirical equation for H-atom. En= - hR/n^2
Professor Lavelle was using an example with transitions from n=4 to n=2.
So it would be (-1/16)*hR and (-1/4)*hR.