Confused about the number of absorption lines

[YMMMA]

Homework Statement

If an atom in energy level 1, how many absorption spectral lines can an atom exhibit due to transition between 3 levels? How about 4 and 5 levels? And also in emission?

Homework Equations

Concept

The Attempt at a Solution

I am confused one book says it can absorb a photon to the third level at once, or to n=2, so there is only 2 possible transitions. Another book says it can absorb once to n=3, n=2, and from n=2 to n=3, so there are 3 possible transitions in total. How am I supposed to count the possible transitions? Here’s a question I encountered, but I need to know how to solve any problems of this kind. Any help is appreciated, Thanks in advance!

 

[haruspex]

one book says it can absorb a photon to the third level at once, or to n=2, so there is only 2 possible transitions. Another book says it can absorb once to n=3, n=2, and from n=2 to n=3, so there are 3 possible transitions in total.

It might come down to the exact wording of the statements. Can you post extracts?

 

[YMMMA]

I forgot to post the problem,too.

 

[YMMMA]

Here they are.

 

[ehild]

I forgot to post the problem,too.

The number of spectral lines are asked "if all transitions were possible ".

 

[YMMMA]

The number of spectral lines are asked "if all transitions were possible ".

So they are indeed three possible transitions.

 

[ehild]

So they are indeed three possible transitions.

Yes.

 

[haruspex]

Here they are.

I see no inconsistency. Some of these texts are considering only transitions from a given level, not all transitions between the levels in the set.

 

[YMMMA]

So why in question 5 didn’t we include transitions from n=3 to n=2 and n=2 to n=1, and n=3 to n=1...

 

[haruspex]

So why in question 5 didn’t we include transitions from n=3 to n=2 and n=2 to n=1, and n=3 to n=1...

Because that question specifies transitions from level 4.
This is not the same as asking for all emission lines, since that would include 3->2, 3->1 and 2->1.

 

[YMMMA]

Got the difference, thanks!