User:Darrell Bonn/Notebook/307L Lab book/lab 5 Millikan

Procedure
Equipment setup
 * 1) 	Measuring the thickness of the plastic between the plates. D for capacitor: 7.75mm, 7.76 on other side
 * 2) 	Cleaned capacitor with dry paper towel, took care to remove any particles
 * 3) 	Placed the focusing wire in place, connected light and focused on the wire
 * 4) 	Adjusted the light to best illuminate the wire exactly as explained in manual. Removed the focusing wire.
 * 5) 	There are 5 small divisions per large division in the viewer grid
 * 6) 	Attached 500 volt power supply.

The procedure can be found online at Pasco's website

density of Squib#5597 Mineral Oil given by manual is 886kg/m^3

Measurements Time measurements are between two major lines Initial Trials – We took a bit of time to simply play with the tools to be sure we understood what we were doing. Barometric pressure: 30.41 in / 1029.7 hPa (from http://www.wunderground.com/US/NM/Albuquerque.html) Measured 500.8 V on the capacitor Temperature within the chamber 26C Added droplets with a single squeeze of the atomizer. Immediately saw drops within the viewer. Picked a small, slow moving one and timed it. Picked a drop, Setting top plate positive, it went up

Data Acquisition
Time data for drop movement is recorded in seconds, no units are put in below to make data easier to copy and paste into other applicatoins Data is also recorded sequentially instead of in a table so that precise time of the temperature readings can be seen Procedure is for one person to watch the drop and control the aparatus, calling out to the next person who has the stop watch. The person with the stop watch records the time in the "lab book". There is some inherent human error in this method, but it seems to be the best we can do with the tools on hand. A good stop watch that records consecutive times would be very helpful to improve accuracy and to speed up acquisition process. It is very tiring watching these drops. Setting the aparatus to a comfortable height is essential as this is a lengthy process and discomfort inhibits good, patient data acquisision. A better sheild around the eye piece would also help. Or better yet, one of those CCD adapters that can project the image to a computer screen.

Day One
Drop 1 Lost drop to view
 * Up under positive charge on top plate: 4.33, 4.10, 4.27
 * Down with both plates grounded: 17.56, 19.24
 * Down with charge on bottom plate:

Drop 2
 * Up under positive charge on top plate: 13.12 17.46 11.27 12.55 11.58
 * Down with both plates grounded: 18.17 19.46 19.86
 * Down with charge on bottom plate:

Drop 3
 * Up under positive charge on top plate: 8.62, 7.36, 7.55
 * Down with plates grounded: 23.08, 26.5, 26.98
 * Down with negative charge on top plate:

Measured temperature: 27C

Drop 4
 * Up under positive charge on top plate: 2.24s, 2.56s, 2.37s
 * Down with plates grounded: 7.17s, 6.46s, 6.81s
 * Down with negative charge on top plate:

Tried for about 10 minutes to change the charge on this drop. No joy.

Day Two
Once we find a candidate and get a few measurements, we will open the ionization source in hopes of getting at least a few of these to change charge.


 * Barometric Pressure: 29.82 in / 1009.7 hPa (Falling)
 * initial temp.: 24C
 * plate voltage: 502V

Drop 5
 * Up under positive charge on top plate: 1.87, 17.42 (behavior has changed)
 * Down with both plates grounded: 18.23, 15.27, 21.40

Drop 6
 * Up under positive charge on top plate:4.90,4.68, 4.12, 4.42, 5.11
 * Down with both plates grounded: 28.72

Plate Voltage: 506V Temperature of chamber: 25.5c

Drop 7 Switched charge, stopped alpha exposure. Up with opposite charge (negative on top plate): 2.58, 2.21, 4.33, 4.70 Appeared to loose charge.
 * Up under positive charge on top plate: 4.81, 4.65, 5.09, 4.73, 5.06
 * Down with both plates grounded: 48.93, 54.83, 55.55

Drop 8 Lost it
 * Up under positive charge on top plate: 3.09, 3.09, 3.21
 * Down with both plates grounded: 93.81

Chamber temp 26.5 Charge on plates: 507V

Drop 9</B> Exposur begins (under + charge no motion occurs, very stable) lost him
 * Up under positive charge on top plate: 10.33, 9.05, 9.17
 * Down with both plates grounded: 10.14, 10.18, 10.05

Drop 10</B> Exposure begins (after a few sec looses charge) lost him
 * Up under positive charge on top plate: 19.02, 18.11, 16.71
 * Down with both plates grounded: 6.09, 5.88, 5.56,
 * Up under positive charge on top plate:
 * Down with both plates grounded: 5.52

Drop 11</B> Exposure begins (won't go up, but can increase speed downwards, thus we determine the oil particle must have been too massive to rise under the force of one e-charge)
 * Up under positive charge on top plate: 22.67, 5.34 (change in charge noticed), 5.70, 5.36
 * Down with both plates grounded: 5.31, 5.90, 5.93, 5.83

Chamber temperature: 27.8c Plate voltage: 507V

Drop 12</B> Exposure begins (charge is quickly reversed)
 * Up under positive charge on top plate: 8.93, 8.84, 4.12, 3.48
 * Down with both plates grounded: 22.00, 22.34, 25.62
 * Up under negative charge on top plate: 3.68, 3.50, 3.65, 3.43, 1.15, 1.15, 1.30, 1.21, 1.36
 * Down with both plates grounded: 22.70, 20.45

chamber temperaturte: 28C

Voltage: 506.5V

Drop 13</B> premature end to data aquisition
 * Up under positive charge on top plate: 2.58, 2.45, 2.98
 * Down with both plates grounded: 17.34,

Drop 14</B> Exposure begins (no change for a while, then noticable slow down) Second Exposure
 * Up under positive charge on top plate: 1.81, 2.00, 1.58
 * Down with both plates grounded: 7.08, 7.63, 7.75
 * Up under positive charge on top plate: 15.53, 20.33, 15.95, 17.81, 19.33
 * Down with both plates grounded: 7.46, 7.87
 * Up under positive charge on top plate: 13.27, 1.15, 1.18, 1.21
 * Down with both plates grounded: 6.59, 7.43

Temperature remains at 28°C.