How Does the Zeeman Effect Alter the Wavelength of Hydrogen's Paschen Lines?

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Homework Help Overview

The discussion revolves around the Zeeman effect and its influence on the wavelengths of the Paschen lines in the hydrogen spectrum, specifically focusing on the transitions from n=4 to n=3. The original poster attempts to identify allowed transitions and calculate the change in wavelength under an external magnetic field.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster grapples with calculating the energy difference and resulting wavelength change for specific transitions, expressing confusion over the magnitude of their results. Some participants offer reassurance about the approach while discussing the importance of constants in quantum mechanics.

Discussion Status

The discussion has seen some productive exchanges, with participants providing guidance on the significance of constants and confirming the correctness of the original poster's approach after a calculation error was identified. There is an ongoing exploration of the implications of the Zeeman effect on the transitions discussed.

Contextual Notes

The original poster mentions a specific external magnetic field strength of 2T and reflects on the expected wavelength range of the Paschen lines, indicating a potential mismatch in their calculations. There is an acknowledgment of the complexity involved in the transitions and the calculations required.

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Homework Statement


The \alpha lines of Paschen in the hydrogen spectrum are due to transitions n=4 \to n=3. Identify the allowed 4p \to 3d transitions and determine the change in wavelength for each transition if there's an external B field of 2T.

Homework Equations


\Delta E=m_l \mu _B B.
E=\frac{hc}{\lambda}.

The Attempt at a Solution


I graphed all transitions possible (it's an enormous mess).
Now say I want to calculate the difference of wavelength of with and without the magnetic field for the transition 4p, m=0 and 3d, m=1 (it's allowed). I have that m_l=1.
So applying the first formula I gave, this gives \Delta E \approx 1.85 \times 10^{-23}J=1.16\times 10^{-4}eV.
Applying the second formula this gives me \Delta \lambda \approx 0.01 m.
I know this result is totally senseless. It's way too big, enormous. From memory Paschen lines are in the near infrared so about 800 nm and a bit up. Nothing like 0.01m!
I really don't know what I'm doing wrong.
I would appreciate some help.
 
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Nevermind, the approach is right. I just made a calculator mistake with the product "hc".
 
Hi! Glad it worked out.

By the way, both eV energy units and the product hc comes up so frequently in quantum mechanics that it's a good idea to remember (or right down, wherever you have a list of physics constants) it's value:

hc = 1240. eV-nm​

The energy-wavelength conversions will go quicker that way.
 
Redbelly98 said:
Hi! Glad it worked out.

By the way, both eV energy units and the product hc comes up so frequently in quantum mechanics that it's a good idea to remember (or right down, wherever you have a list of physics constants) it's value:

hc = 1240. eV-nm​

The energy-wavelength conversions will go quicker that way.

Thank you for your concern. And yes, I agree with you, I'll get "hc" in eV*nm into my formula sheet.
 

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