User:Chad A McCoy/Notebook/Jr. Lab/2008/10/13

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Balmer Series Lab: 10/13/2008

  • For the Lab covering the weeks of 10/13/2008 and 10/20/2008, I have chosen to do the Balmer series, where after calibration of an optical spectrometer, I will measure the spectral lines of hydrogen and deuterium.
  • For the Lab, I am using a model SP200 5000 Volt, 10mA Spectrum Tube Power Supply, produced by Electro-Technic Products, using spectral tubes of mercury, hydrogen, and deuterium.
  • For measuring the data I am using a "constant-deviation" spectrometer, with a Pellin-Broca constant-deviation prism acting to determine the different wavelengths.
  • The full procedure can be accessed in Professor Gold's Lab manual here
Measured values vs. known values of Mercury spectral wavelengths
Known Values Measured Values
404.7nm 404.2nm
435.8nm 435.9nm
546.1nm 546.0nm
577.0nm 576.9nm
579.0nm 579.0nm
690.75nm 700.0nm
  • When calibrating the spectrometer, I had a wide variance in measurements, and had extreme differences in measurements depending on the wavelength. I settled on zeroing the spectrometer such that it had the closest values for the 546.1 and 577 nanometer readings and ignore that the red line had a significantly higher reading than what would be expected.
Measured values of Hydrogen spectral wavelengths
Line 1 2 3
1 409.4nm 409.6nm 409.3nm
2 433.1nm 433.3nm 433.2nm
3 484.8nm 485.0nm 485.0nm
4 654.3nm 654.1nm 654.0nm
Measured values of Deuterium spectral wavelengths
Line 1 2 3
1 409.4nm 409.3nm 409.5nm
2 433.2nm 433.1nm 433.2nm
3 484.5nm 485.0nm 484.8nm
4 654.1nm 653.8nm 654.5nm
  • My method of measurements was to start at the highest wavelength possible and work my way down the spectrum, taking measurements as I go. After finishing a set of measurements for Hydrogen, I switched to the deuterium and took my measurements. I repeated the set 3 times, without touching the crystal and possibly changing the calibration in between sets.
  • After completing these measurements, I decided to take another set of data with a different calibration so that I would have another calibration slope, hopefully giving more accurate results.
  • For these data sets I am measuring from the lowest possible wavelength on the spectrometer up, with the calibration done first then hydrogen then deuterium.
Measured values vs. known values of Mercury spectral wavelengths
Known Values Measured Values
404.7nm 404.5nm
435.8nm 435.8nm
546.1nm 545.9nm
577.0nm 577.1nm
579.0nm 579.5nm
690.75nm 699.1nm
Measured values of Hydrogen spectral wavelengths
Line 1 2 3
1 409.7nm 409.8nm 409.9nm
2 434.0nm 433.9nm 434.0nm
3 485.7nm 485.7nm 485.8nm
4 656.0nm 657.0nm 656.8nm
SJK 00:18, 3 November 2008 (EST)
00:18, 3 November 2008 (EST)Looks like you did some deuterium measurements, but did not crunch the numbers, right?  Well, it does look like they're indistinguishable in your measurements.
00:18, 3 November 2008 (EST)
Looks like you did some deuterium measurements, but did not crunch the numbers, right? Well, it does look like they're indistinguishable in your measurements.
Measured values of Deuterium spectral wavelengths
Line 1 2 3
1 409.8nm 409.7nm 410.0nm
2 433.9nm 433.9nm 434.0nm
3 485.0nm 485.3nm 485.4nm
4 656.1nm 656.5nm 656.8nm
  • The last portion of the lab asks for us to measure the resolving power of the spectrometer using Sodium and the double yellow spectral lines at 589.0 and 589.6 nanometers. Unfortunately, we do not have a spectral tube containing sodium vapor, so I was unable to see if it was possible to measure the difference between the two lines.


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