Intensity-wavelength graph for emission spectra; why is frequency in the x-axis?

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SUMMARY

The discussion centers on the use of frequency on the x-axis of intensity-wavelength graphs for emission and absorption spectra, as presented in "Astrophysics" by Nigel Ingham. The preference for frequency over wavelength is attributed to its linear relationship with energy, allowing for a clearer understanding of energy levels across the spectrum. Additionally, the Planck function can be represented in terms of either wavelength (lambda) or frequency (nu), indicating flexibility in graph representation. To convert frequency-based graphs to wavelength-based ones, one must apply the relationship between frequency and wavelength.

PREREQUISITES
  • Understanding of the Planck function in blackbody radiation
  • Knowledge of the relationship between frequency and wavelength
  • Familiarity with emission and absorption spectra
  • Basic concepts of energy quantization in astrophysics
NEXT STEPS
  • Study the Planck function and its applications in astrophysics
  • Learn how to convert between frequency and wavelength in spectral analysis
  • Explore the implications of using frequency versus wavelength in graphing spectra
  • Investigate the significance of energy levels in emission and absorption processes
USEFUL FOR

Astrophysicists, students of physics, and anyone interested in the analysis of emission and absorption spectra in astrophysics.

slakedlime
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In my astrophysics book (Astrophysics, Nigel Ingham), there are intensity-wavelength graphs for line spectra (both emission & absorption). On the y-axis, relative intensity is plotted. But on the x-axis, frequency and not wavelength is plotted. Why is this? If I wanted to convert this graph to an actual intensity-wavelength graph (e.g. like one for a black body), what would I have to do?
 
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Just remember how frequency and wavelength are linked... The choice is relatively arbitrary.
 
I like frequency better. It has the advantage that it scales linearly with energy, so that you know that the rightmost end of the graph corresponds to high energies, and the leftmost end to low energies.

I'm not sure why you seem to think that plots of the Planck function (blackbody radiation) are always in terms of wavelength. The Planck function can be expressed in either form (as a function of either lambda or nu).
 

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