# Calculating the wavelength for series limit for the Paschen series

1. Sep 9, 2006

### vanabariel42

Hi. I'm having some trouble calculating the wavelength for series limit for the Paschen series.
I've set the Rydberg equation up with 1/(n sub f squared) as 1/(3 squared), but I'm not sure what goes in for 1/(n sub i squared) as the initial position.
I'd appreciate any help. Thanks!

2. Sep 9, 2006

### Staff: Mentor

The Paschen series describes transitions from a higher level down to n = 3. So $n_f = 3$ and $n_i > 3$

3. Sep 9, 2006

### vanabariel42

That I know, but what number corresponds to the series limit? Some places said 14, others said 12, and others infinity. I'm not sure how to use infinity in a calculation though.

4. Sep 9, 2006

### Staff: Mentor

Lucky for you all you need to use is 1/infinity. What's that?

5. Sep 9, 2006

### vanabariel42

that's a good question.

6. Sep 10, 2006

### Staff: Mentor

Try this:
$$\frac{1}{\infty} = 0$$

7. Sep 10, 2006

### Gokul43201

Staff Emeritus
That you're asking this question means you do not understand what is meant by the term "series limit". Please make sure you understand what it means. If not, ask and find out.