Discovery of how to measure wavelength absorption lines

  • I
  • Thread starter Ava_Seven
  • Start date
  • #1
7
0

Main Question or Discussion Point

who was the first person to discover how to measure the wavelength of
absorption lines in the solar or stellar spectra and what method was used?
 

Answers and Replies

  • #2
Simon Bridge
Science Advisor
Homework Helper
17,847
1,644
  • #3
7
0
Have you tried entering "discovery of solar absorbtion lines" into google?
https://en.wikipedia.org/wiki/Fraunhofer_lines
I understand that Fraunhofer's measured wavelengths of spectral lines and that he had scribed a diffraction granting with 50000 grooves per inch and had used it for that purpose, getting results for the sodium doublet close to modern values. Regarding his procedure, was he the first or was it Augusti Fresnel or someone else? And what unit did they use?

In 1801 Thomas Young used his experiments with double slits to measure wavelengths of the seven rainbow 'colours' described by Newton and got respectable results. Still don't know the units though.
 
  • #4
davenn
Science Advisor
Gold Member
2019 Award
9,133
7,103
I understand that Fraunhofer's measured wavelengths of spectral lines and that he had scribed a diffraction granting with 50000 grooves per inch and had used it for that purpose, getting results for the sodium doublet close to modern values. Regarding his procedure, was he the first or was it Augusti Fresnel or someone else?
did you actually read the Wiki link given to you ?
it answered your Q

there is no mention of Augusti Fresnel being involved with emission/absorption lines discovery either in that link or in the wiki entry for Augusti Fresnel

D
 
  • #5
7
0
did you actually read the Wiki link given to you ?
it answered your Q

there is no mention of Augusti Fresnel being involved with emission/absorption lines discovery either in that link or in the wiki entry for Augusti Fresnel

D
Yes I did read the link. No need to be rude. This is a debate/discussion in one of my classes, and the question is generate thought beyond Wiki. Just because Wiki doesn't mention it, doesn't mean those people mentioned didn't do what was said.
 
  • #6
davenn
Science Advisor
Gold Member
2019 Award
9,133
7,103
Yes I did read the link. No need to be rude.
wasn't being rude :smile:

your response hinted that you didn't read the link or do any further study
that last bit which is particularly encouraged here on PF

The wiki link told you the name of the person that first noticed the dark bands in the spectrum
but you didn't bother to mention that name, rather went on to other names that weren't in the link
 
  • #7
Simon Bridge
Science Advisor
Homework Helper
17,847
1,644
Yes I did read the link. No need to be rude. This is a debate/discussion in one of my classes, and the question is generate thought beyond Wiki. Just because Wiki doesn't mention it, doesn't mean those people mentioned didn't do what was said.
This is vital information you left out.

It's odd to find that you are asked to go beyond wikipedia for a question that is completely answered within wikipedia ...
The questions were:
who was the first person to discover how to measure the wavelength of
absorption lines in the solar or stellar spectra...
Johannas Fraunhofer
.. and what method was used?
diffraction spectroscopy

Further questions were:
I understand that Fraunhofer's measured wavelengths of spectral lines and that he had scribed a diffraction granting with 50000 grooves per inch and had used it for that purpose, getting results for the sodium doublet close to modern values. Regarding his procedure, was he the first or was it Augusti Fresnel or someone else?
Fraunhofer was first. Since you read the link, you ready the bit right at the start that said:
In 1814, Fraunhofer independently rediscovered the lines and began a systematic study and careful measurement of the wavelength of these features.
... under "Discovery". I suppose it does not actually state in so many words that Frounhofer was first, but it also does not put any others before him.
You can use this information to refine your googling to confirm the result if you want to be absolutely sure.
You can also look up the references wikipedia supplies for this information or use the titles as clues for further google searches:
  1. Hearnshaw, J.B. (1986). The analysis of starlight. Cambridge: Cambridge University Press. p. 27. ISBN 0-521-39916-5.
  2. Joseph Fraunhofer (1814 - 1815) "Bestimmung des Brechungs- und des Farben-Zerstreuungs - Vermögens verschiedener Glasarten, in Bezug auf die Vervollkommnung achromatischer Fernröhre" (Determination of the refractive and color-dispersing power of different types of glass, in relation to the improvement of achromatic telescopes), Denkschriften der Königlichen Akademie der Wissenschaften zu München (Memoirs of the Royal Academy of Sciences in Munich), 5: 193-226; see especially pages 202-205 and the plate following page 226.
From the sounds of things - this is what the exercise is all about. "Going beyond wiki" does not usually mean "ask someone else".... rather you should do your own research. We can point you in the right direction but you have to to the work yourself.

And what unit did they use?
The inch.

In 1801 Thomas Young used his experiments with double slits to measure wavelengths of the seven rainbow 'colours' described by Newton and got respectable results. Still don't know the units though.
Also inches ... Young developed the technique of diffraction spectroscopy used by Fresnel and others ... Fresnel has nothing to do with the question in post #1.

But if you want to be sure, you can use google to look for references to these people making wavelength measurements of the dark lines in the solar spectrum.
What sort of search term could you use?[/quote][/quote]
 

Related Threads on Discovery of how to measure wavelength absorption lines

Replies
21
Views
4K
  • Last Post
Replies
18
Views
5K
  • Last Post
Replies
1
Views
4K
Replies
3
Views
621
Replies
2
Views
892
  • Last Post
Replies
5
Views
3K
Replies
2
Views
759
Replies
2
Views
2K
  • Last Post
Replies
9
Views
5K
Top