User:Jacob R Jaramillo/Notebook/Electron Diffraction

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SJK Incomplete Feedback Notice
Incomplete Feedback Notice
My feedback is incomplete on this page for two reasons. First, the value of the feedback to the students is low, given that the course is over. Second, I'm running out of time to finish grading!
SJK 22:36, 19 December 2009 (EST)
22:36, 19 December 2009 (EST)
As with e/m, notebook and summary are a bit sparse. Glad you enjoyed the experiment!
  • As always when dealing with electricity, be care not to touch any exposed metal on the banana clips when pluging in connections and when removing connections.
  • Use cation when handeling the Electron Diffraction Tube as not only is it an expensive peice of equipment, it can shatter and cut you.
  • Be careful not to exceed the maximum current load to the Electron Diffraction Tube as the graphite can be damaged with more than 0.25mA.


  • Electron Diffraction Tube


  • KV power unit


  • HP power supply 6216B (line 115V +/-10%)


  • Wavetek voltmeter


  • Numerous black and red banana cables


Dr. Golds Lab Procedure

Schematic of wiring

The set up is definitely best explained by the above Schematic of wiring linked above. With two important notes from Dr. Golds Lab Procedure that I wanted to stress: Switch on the heater supply (VF ), and wait one minute for the cathode temperature to stabilize before applying the HV (anode voltage VA) and be sure the high voltage slider is at zero before switching on the unit.

Once the equipment is all turned on, you can proceed to increase the voltage to ~3.5kV which is the approximate volate required to see the electron diffraction rings. You can also use the magnet to center your rings on the center of the tube, by rotating it around the narrow neck of the tube.

When you have centered the rings with respect to the tube to the best of your ability, you are now ready to take measurements. Measure the diameter of the inner ring and outter ring and record the voltage applied in kV's.


Electron Diffraction values and calculations

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To date this was one of the most difficult labs for me due to the uncertianty and difficulty of measuring the ring diameter. I used calipers which are extremely accurate (+/-0.1mm that is); however, the line of the ring was very blurry so the best attempt I could make was to measure the outter most portion of the ring and keep this consistant throughout the experiment. It is also important to note that in the lowest voltage settings (~3.5KV) it was extremely difficult to see the rings; therefore, quite a bit of guestimating took place.


Electron Diffraction Summary


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