User:Ryan P. Long/Notebook/Physics 307L/2009/10/26: Difference between revisions

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==Analysis==
==Analysis==
Though I couldn't put it into words at the time, I think the reason the gridlines were hard to make out using the cameras was that the gridlines were spaced so close together on the camera screen that sometimes multiple lines would be seen by the same pixel. This would explain the random spacing of what appeared to be "darker" lines rather than the thicker lines spaced every .5 mm apart.
Although the cameras did not work as well as we had hoped, it was still rather interesting to set up each camera and experiment with each.  Perhaps they did not work properly because of the optics on the Millikan apparatus, since they are in fact designed to be used with the eye instead of a camera.


As in the first experiment, I calculated my value of Atmospheric pressure, using  [http://earth.google.com Google earth] to find the elevation near campus (5187 ft.), and then calculated the pressure with an excellent converter that can be found [http://www.turblex.com/altitude/index.cfm here].
As in the first experiment, I calculated my value of Atmospheric pressure, using  [http://earth.google.com Google earth] to find the elevation near campus (5187 ft.), and then calculated the pressure with an excellent converter that can be found [http://www.turblex.com/altitude/index.cfm here].

Revision as of 17:22, 8 November 2009

Millikan Oil Drop Experiment Round 2 <html><img src="/images/9/94/Report.png" border="0" /></html> Main project page
<html><img src="/images/c/c3/Resultset_previous.png" border="0" /></html>Previous entry<html>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</html>Next entry<html><img src="/images/5/5c/Resultset_next.png" border="0" /></html>

Note: My partner Tom and I share the same lab notebook up to the Analysis section

Equipment

Pictures from the Original Experiment

  • Millikan Apparatus setup

    Millikan Apparatus setup

  • Ryan squeezing some oil into the chamber

    Ryan squeezing some oil into the chamber

  • Close up of the capacitor plates

    Close up of the capacitor plates

  • Top view of the Apparatus

    Top view of the Apparatus

Pictures from the Continuation

  • Brighter LED Light Source

    Brighter LED Light Source

  • Creative Web Camera

    Creative Web Camera

  • CCD Camera

    CCD Camera

  • CCD with Lens

    CCD with Lens

Equipment used in both the original experiment and the followup

  • Pasco Scientific AP-8210 Millikan Oil Drop Apparatus
  • Mineral Oil
  • SMIEC Micrometer
  • Wavetek 85XT Multimeter
  • TEL-Atomic 500V DC Power Supply

New equipment

  • Light similar to the Magnoclip LED Work Light & Laser Pointer
  • Creative USB webcam
  • Logitech USB webcam
  • CCD camera (typical for use in an optics lab)
  • 2" plano convex lens with focal length ~10cm
  • Canon XH-A1 HDV Camera + tripod

Note: We forgot to write down the model numbers of the Logitech, Creative, and CCD cameras, but we will get this information the next time we are in the lab

Week 1- No Camera

Setup

First, we tried using the Creative and Logitech webcams to see the droplets and take data. Then we ended up just following the procedure we used in the original experiment.

Data

First, we set up the Logitech camera. The focusing wire was easily seen, but the gridlines were hard to make out due to the camera's low resolution. We tried the same thing with the Creative camera, but again, the gridlines were hard to distinguish from one another. After putting the drops in for both cameras, the light was not bright enough to see anything, despite changing cameras' integration times, contrast, and brightness settings.

After our attempts with the cameras yielded no data, we took data in a similar fashion as the original experiment: we squirted some mineral oil into the chamber with the ionization source set to the spray droplet position. We then turned it off, played with the capacitor plates until we found a suitable drop, and proceeded to time it as it rose with the force of the electric field and fell due to gravity. We did not repeat our previous mistake of measuring the fall time of the droplet WITH the electric field on.

Raw data sheet: {{#widget:Google Spreadsheet

key=tdqXMh97xXnU0W-obvdhVEA width=650 height=300

}} I decided to name our droplets for added excitement

Analysis

Although the cameras did not work as well as we had hoped, it was still rather interesting to set up each camera and experiment with each. Perhaps they did not work properly because of the optics on the Millikan apparatus, since they are in fact designed to be used with the eye instead of a camera.

As in the first experiment, I calculated my value of Atmospheric pressure, using Google earth to find the elevation near campus (5187 ft.), and then calculated the pressure with an excellent converter that can be found here.


The charge was calculated using the formula on page 9 in the Pasco Manual.

The accepted value of the charge of a single electron is (from wikipedia):

e = [math]\displaystyle{ 1.602176487(40) \cdot 10^{-19} }[/math]C

Week 2- Camera

Setup

For the second week we intended to use a camera to make the data taking process easier to see, and possibly more precise due to the use of recording and the ability to analyze the data frame by frame instead of using a stop watch. First, we set up my video camera to look at the droplets. Before moving to the next camera, we removed the lamp housing with the incandescent bulb in it and replaced it with LED light. We tried to view it again with my camera. Finally we set up the 2" lens behind the eyepiece and put the CCD camera at a distance about 10 cm away (we moved it until it looked to be most in focus).



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