Physics307L F09:People/Franco/Franco's Balmer

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Balmer Summary

SJK 02:08, 23 October 2008 (EDT)
02:08, 23 October 2008 (EDT)
You did a very good job on this lab. You and David took some very good and careful data and your excel sheet is really great and easy to read. My main criticism below is that you do not have units on your final Rydberg constant and you do not use the uncertainty to compare with accepted value. Also, as I noted, you should upload your nice figures somewhere either in your summary or your notebook!

Accepted Values for H [1] Wavelength (nm)

  • 656.3
  • 486.1
  • 434.1
  • 410.2

Our Values for H

  • 656.1 +/- .5 nm
  • 486.00 +/- .04 nm
  • 434.1 +/- .1 nm
  • 409.7 +/- .1 nm

Our Values for D

  • 659.13 +/- .03 nm
  • 485.95 +/- 0.03 nm
  • 434.2 +/- 0.1 nm
  • 409.65 +/- .12 nm

From the data, the only ones that were precise (Steve Koch:I think you mean "accurate") were 3rd and 4th measurement. As for the 1st and 2nd those were not as precise. One thing that could have offset the measurements is that we only calibrated using the 434.1 nm. Even though we were avoiding "slop," calibrating it only based on that measurement sets a systematic error. Another possibility is error input in the data, we notice we had put a wrong measurement, and corrected it. But who's to say there isn't anymore of those errors. Another is the method of how the dial was read. Was it eye level consistently or was that even considered?

Rydberg experimental constant: 1.0975E+07 (+/- .0003) SJK 02:21, 22 October 2008 (EDT)
02:21, 22 October 2008 (EDT)
Where are the units on this final value?
The Rydberg constant was measured with a .0175(25)% difference. Our Rydberg constant was not too far off from the accepted value as mentioned in the lab notebook.SJK 02:22, 22 October 2008 (EDT)
02:22, 22 October 2008 (EDT)
I agree that you have obtained very nice results! However, "not too far off" is always relative. You should put the accepted value here, and then compare the discrepancy from your answer with your uncertainty...this is the statistical way to compare them

Things I would improve on after doing this lab are: one I would talk more measurements and calibrate not just on one, but instead on the other wavelengths. Secondly, I would focus more on being much more consistent with eye level and writing down data.