User:Emran M. Qassem/Notebook/Physics 307L/2010/10/04: Difference between revisions
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We had a lot of trouble with this lab in terms of particles disappearing, jumping in speed, moving from side to side, suddenly reducing in fall times, and so on. We also watched these particles for long periods of time which was physically straining as after a period of time our eyes would water and we would lose the particle. | |||
One of the biggest causes for error I believe would be a particle changing mass over time as it evaporates. Another would be human error as one person was watching and saying start and stop while the other person operated the stop watch. | |||
As you can see, in the end when we were tired, particle 5 had the worst data measurements and had the most inconsistent rise and fall times. | |||
==Acknowledgments/Citations== | ==Acknowledgments/Citations== |
Revision as of 18:16, 21 December 2010
Millikan Oil Drop | <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> </html>Next entry<html><img src="/images/5/5c/Resultset_next.png" border="0" /></html> | |||
PurposeThe main purpose of this lab is to calculate the charge of a single electron. The way to do this is to observe the fall and rise times of many charged drops of oil in an electric field so as to calculate the discrete charge of one electron by noticing that the charge on each oil drop is a multiple of a specific discrete value. Equipment
SafetyThere are a few safety concerns in this lab:
Setup
Procedure
Data{{#widget:Google Spreadsheet |
key=0Akva81bvmQvLdHJqQTBnaUZLeGhjVTUyc3JKQ29OR3c | width=800 | height=600
}} CalculationsParticle 1 and 3 did not last, so they are not included in the calculations. Some of the droplets had big jumps in the rise times, so we disregarded those data points. Averages are calculated by taking the accepted data points, summing them up and dividing by the number of points. Standard deviation is calculated by taking the difference of the data point and the average value, squaring it, summing these results and dividing by the number of trials, then taking the square root of the result. Calculating Charge This has 3 steps:
Using accepted value for charge of an electron is 1.6 * 10^(-19) C, we can estimate how much charge a particle will have and divide by the number of charges we guess to see our calculated value for the charge of an electron.
Particle 2
Calculating Charge
Particle 2 has approximately: 3 * e charge. Calculate e to be: 1.4(1) * 10^(-19) C Particle 4
Calculating Charge
Particle 4 has approximately: 1 * e charge. Calculate e to be: 1.2 * 10^(-19) C Particle 5
Calculating Charge
Particle 5 has approximately: 1 * e charge. Calculate e to be: 2(2) * 10^(-19) C ResultsWe got these 3 charges:
The accepted value is:
The first calculation is off by two sigma from the accepted value, the second we did not calculate standard deviation but it's a little further off, and the third has a huge error. ErrorWe had a lot of trouble with this lab in terms of particles disappearing, jumping in speed, moving from side to side, suddenly reducing in fall times, and so on. We also watched these particles for long periods of time which was physically straining as after a period of time our eyes would water and we would lose the particle. One of the biggest causes for error I believe would be a particle changing mass over time as it evaporates. Another would be human error as one person was watching and saying start and stop while the other person operated the stop watch. As you can see, in the end when we were tired, particle 5 had the worst data measurements and had the most inconsistent rise and fall times. Acknowledgments/CitationsRandy for calculations and ideas during the lab. Dr. Gold's manual for suggesting the cleaning.
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