User:Alex G. Benedict/Notebook/Physics 307L: Junior Lab/Balmer Series Lab
Steve Koch 04:18, 21 December 2010 (EST):Good primary lab notebook, but a little more detail necessary to ensure reproducibility.
Balmer Series Lab
This lab was performed in the junior laboratory in the UNM physics building on October 25 and November 1, with Joseph Frye.
Links
Equipment and Setup
Thanks to David K. O'Hara for the specific model numbers of the equipment used. O'Hara's Lab from 2009
- Adam Hilger London Spectrometer. Serial Number 12610
- Spectrum Tube Power Supply Model SP200 5000V 10 mAmps
- Spectrum Tube, Mercury Vapor S-68755-30-K
- Spectrum Tube, Hydrogen S-68755-30-G
- Spectrum Tube, Deuteruim S-68755-30-E
Set up for this lab involved putting a tube in the power supply and aiming the spectrometer towards the tube. Also putting some books under the power supply to elevate it.
Procedure and Data
We followed the procedure in the lab manual linked above. On the first day we followed the calibration procedure on this page: [Balmer]. On the second day, we first observed the spectral lines from the Hg source for a few trials moving forwards and then backwards. We did this to account for the slight shift in the measured position of the spectrometer due to improper gear meshing. Then created least squares fits for the forwards and backwards trials. Which were then used to correct measurements taken that day. We then observed the locations of the spectral lines of the H and D.
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Results
We know from the Rydberg formula that R=1/((wavelength of the light)*(1/4-1/n^2)), the accepted value is 0.0109737316 nm^-1 for hydrogen. And using the definition of the Rydberg constant, it should be 0.01097072 for Deuterium.
For the first day:
We get for hydrogen:
R=0.01098308+/-0.000027
Which gives a relative error of 0.00085 and a fractional error of 0.0024
and for Deuterium:
R=0.01098897 +/-0.000021
Which gives a fractional error of 0.0019 and a relative error of 0.00055
For the second day:
For H:
R=0.01099695+/- 0.000026
Which gives a relative error of 0.0021 and a fractional error of 0.00241
For D:
R=0.01098152+/-0.000022
Which gives a fractional error of 0.002 and a relative error of 0.001
Overall there was very good data, and the experiment went very well.
