User:David J Weiss/Notebook/notes Balmer

Balmer Series

In this expernment we will find through expernmentation the value of the Rydberg Constant through the observation of spectral lines of the Hydrogen Atom and the Deuterium Atom. To do this we will excite the atoms of the Hydrogen and Deuterium by means of electric stimulation of the gas to excite the electrons in the gas to highter energy levels. When the electrons go back into the orignal energy levels they emit a photon whose wavelength is equal to the amount of energy of the electron.

Equipment

• Constant-Deviation Spectrometer
• Spectrum Tube Power Supply Model SP200 5000V
• Spectrum Tube, Mercury Vapor S-68755-30-K
• Spectrum Tube, Hydrogen S-68755-30-G
• Spectrum Tube, Deuteruim S-68755-30-E

Setup

Set Up of Balmer Lab

The set up of this lab is as follows:

• Position the Constand-Deviation Spectrometer so you can have to view the Gas tubes
• Adjust the Height of the Spectrum Tube Power Supply so you can view the tubes through the eyepeace of the Spectrometer
• Place the tube into the Spectrum Tube Power Supply
• Plug the spectrum Tube Power Supply in and turn it on
• Adjust the prism so you can view the spectral lines of the Mercury Vapor

Safety

This lab has the following safety concerns:

• Electrical Shock: due to the fact that the gasses are excited through electrical means there is a safety concern that the equipment due to the fact that it runs on electricity will shock you
• Glass Tubes: glass may break and cut your skin and also make sure you do not inhale the gasses contained within the tubes
• Mercury Gas: toxic gas that can cause bodily harm if inhaled
• Care of the insterments
• Dont Drop things on your self

Notes

Day 1

• worked with Elizabeth Allen and thanks for all the help
• first we went thruogh the safety brief with Dr Koch and Pranav Rathi
• then we set up the lab we had to use several books to adjust the hight of the lamp in relation to the Spectrometer
• then we got the equipment and started to calbrate the Spectrometer with mercury vapor by adjusting the prism and then adjusting the screw drive till we were able to view the mercuy lines. We also had to adjust the width of the slit while calibrating the spectrometer. While calibrating the spectrometer we would start with the green at 546.1nm then calibrated the yellows from there a yellow line at 576.4nm the manual says it should be at 577 nm an error of about .6 nm, another yellow line at 578.5nm which is off by .5nm, and a red line at 701nm which is not what the manual says should be at 690.75 an error of about 10.25nm. We then went to look at the viloet at 435.9nm which was off the manuals by .1nm, the second viloet line was at 404.5nm the book value is 404.7nm a difference of .2nm.
• while adjusting the screw drive we needed to be careful of the slop or play in the gears and make sure to keep the spectral lines in the crosshairs of the eyepeace
• we decied to use a narrow light instead of a wide light sacraficing the intensity of the light for a better resoulution of the spectral lines
• after we calibrated the Spectrometer we then measured the specral lines of the hydrogen gas below. The first line we observed was the volet line followed by the blue-green lilne then the red. We were a little confused about what the actual spectral lines were but we decied upon two in the range of yellow spectral lines.
• we measured the Deuterium the first spectral line we observed was the red line, followed by the viloet line, then the blue-green line. a yellow line was observed followed by an orange line but both of them were more faint than the others.

Day 2

• on day two i worked with elizabeth allen again.
• used several books again to get the proper hight of the lamp and turned on the lamp to let it warm up for 5 minutes. after that i opened the slit using the screw drive so i can calibrate the scope.
• i then adjused the prism using the mercury vapor to calbrate the scope starting with the green spectral line at 546.1 nm. after finding the green spectral line i then went to the violet at 435.9nm which is off from the expected value by .1nm. after seein the viloet we went back to the green and found the red at 697nm off about 7.75nm. then the yello lines at 579.7nm off about .7nm and the 2nd yellow line at 577 which is the value given in the manual.
• after calibrating the spectrometer we then went to measure the spectral lines for hydrogen. the first line was the viloet. we measeured it 5 different times. then repeated for the red, then the yellow and then the orange ending the hydrogen with the bluegreen spectral line.
• we then started to measure the spectral lines of the deuterium starting with red but upon looking we could olny find the red and the blue-green. we could not find any other spectral so we olny have the readings for the red and blue-green for the deuteruim.

Data Day 1

Hydrogen Data

Voloet: 434.1nm

Blue-Green :486nm

Red: 660nm

Yellow: 580.8nm

Orange: 604.8nm

Deuterium

Red: 659.1nm

Volet: 434.3nm

Blue-Green: 486.3nm

Yellow: 584.1nm

Orange: 618.8nm

Data Day 2

Hydrogen

Viloet: 433.8nm, 434nm, 433.9nm, 434.2nm, 434.3nm

Red: 657.6nm, 657.0nm, 657.6nm, 577.7nm, 657.4nm

Yellow: 582.4nm, 582.7nm, 582.6nm, 582.9nm, 582.4nm

Orange: 603.3nm, 604.0nm, 603.9nm, 603.7nm, 603.6nm

Blue-Green: 486.3nm, 486.0nm, 486.2nm, 485.9nm, 485.9nm

Deuterium

Red: 657.8nm, 656.7nm, 657.2nm, 658.2nm, 656.6nm

Orange:

Yellow:

Blue-Green: 485.2nm, 485.6nm, 485.2, 485.2nm, 485.2nm

Viloet:

Data Averages

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Hydrogen

Red: 657.88nm

Orange: 603.88nm

Yellow: 582.3nm

Blue-Green: 486.05nm

Viloet: 434.05nm

Deuterium

Red: 660.6nm

Orange: 618.8nm

Yellow: 584.1nm

Blue-Green: 585.45nm

Viloet: 434.3nm

Errors

• errors can be made in adjusting the width of the slit in that the intensity of the light coming through is diminished and that may cause problems when trying to identify spectral lines that might not be that intense and could be missed.
• more errors can come from the gear back lash in terms of how the gears dont completely mesh up when adjusting the screw in opposite directions so you need to take that into account when adjusting the screw
• i bleve that we looked at different orange lines from day one to day two so thats why the values are off for the orange lines on hydrogen from day one compared to day two
• another error from day one compared to day two is that we could not see all the same spectral lines in Deuterium that we saw on day 1 compared to those we say on day two. we seemed to lose 3 of the spectral lines i dont know why but it happned that way.

Referances

Phyc 307L page Balmer Notes

Dr Golds Lab Maunual

David's Home

David's Notebook