# Line spectrum of hydrogen.

1. Jun 29, 2011

### vkash

no of line in line spectrum is equal to jumps of electron from one shell to another. Am i correct.

IN my book it is written that if a electron in hydrogen jumps from n1 to n2 then number of spectral lines is given by formula {(n1-n2)(n1-n2+1}/2. so consider a electron jump from 4th shell to 2nd shell then number of kinds of jump can be (1) 4th to 3rd,(2) 4th to 2nd So there are only two jumps. but if we apply formula then it will come out to be 3. So where i or formula is wrong.
thanks for any kind of help.

2. Jun 29, 2011

### SpectraCat

3. Jun 29, 2011

### vkash

dear 4th 3rd and 2nd represent the energy level of hydrogen atom n1 and n2 represent the given energy level. Do you got it.

4. Jun 29, 2011

### SpectraCat

Yes, "I got it". You asked what the "third" transition was that is possible in the manifold of levels including 4,3, and 2. I told you the answer. The formula is correct, you just missed a transition with your initial analysis.

5. Jun 29, 2011

### vkash

what's that transition is that 3rd to 2nd. other transitions are already mentioned above.

6. Jun 29, 2011

### SpectraCat

Do you understand what you already wrote? I mean from the 3rd shell to the 2nd shell. Just like you "already mentioned" 4th shell to 3rd shell, and 4th shell to 2nd shell.

Draw yourself a picture, using stacked horizontal lines to represent the states (2, 3 and 4), and downward arrows to represent the transitions. You should see that there are 3 possibilities almost immediately.