User:Darrell Bonn/Notebook/307L Lab book/lab6Summary

Balmer Lab Summary

Lab Partner: Boleszek [1]

In this lab we were asked to determine the Rydberg constant using a constant deviation spectrometer and a known light source.

The spetctrometer was first calibrated to the hydrogen spectrum using 4 calibrations on each of the primary spectral lines. Once calibrated 4 sets of data were then acquired for each calibration. The mean of this was then taken at each spectrum to get the final value used for calculating the Rydberg constant.

Knowing that the data should fit 1/R=lambda(1/4-1/n^2),n=3,4,5... We calculated possible values for the Rydberg constant, plotted the data and selected the value that was constant for all the spectrum. This also gave us the values of n=3, 4, 5 and 6 for red, blue-green, violet 2 and violet 1 respectively.

Our calculated value is R = 1.0934E7 +/-1.234E5 (see below)

After this calculation we also took data on deuterium in an attempt to observe the differences in energy level that would occur from the presence of an extra neutron. However, the differences between hydrogen and deuterium were well within our margin of error and are therefore not of any great value.

Notes on Errors and Calculations

To check the spectrometers consistency, data was acquired two more times at the final calibration. It was seen that we were able to repeat our measurements closely, and that the primary source of our variance would come from the calibration. As a final check on the instruments capabilities, the resolution was checked using a kryptonite light source. This has a large number of closely spaced spectral lines so that we could check the limits of resolution. Again, it was determined from this that resolution was not an issue for this experiment.

The largest standard deviation on any set of acquired data was in the red spectrum and was 5.50nm. We took this as a worst case value and added it back into all the raw data. Recalculating, we see the value of R changes by +/- 1.234E5.

Most data calculation was made in matlab [| balmerlab.m]

Data is located here: [| Notes]