Recreating the Millikan Experiment: Analysis and Error Considerations

In summary, the conversation discusses the recreation of the famous Millikan oil drop experiment in a laboratory setting. The results, based on 120 data points, show two distinct clusters on a histogram of charge vs frequency, which can provide insight into the unit of charge being determined. The graph of calculated droplet radius vs charge also shows distinct clusters centered around a common charge value. The next step is to analyze the potential sources of error and determine the best method for doing so. Suggestions are given, such as using a Gaussian approximation to the histogram, and personal experiences with the experiment are shared. The experiment yielded a value of 0.8 x 10-19 Coulombs.
  • #1
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We've had to recreate the famous Millikan oil drop experiment in our labs and taken values of the velocities of oil drops under the influence of gravity and charged capacitor plates and the balancing voltage required to stop the droplet from moving up or down.

We took 120 results and they look promising. On a histogram of charge vs frequency there appear two peaks that the data cluster around. The difference between these peaks should give an indication of the unit of charge that we're trying to determine. Similarly on a graph displaying the calcculated radius of the droplet vs charge, there are distinct clusters centrered around a common charge value (yet to be determined).

I'm now wondering how to go about looking into error. There are so many ways to approach the analysis and I was wondering if anyone who may have performed the experiment themselves could comment on what they think is the best method. Should I use a Gaussian approximation to the histogram?

Would be very grateful for advice and can elaborate on any details you need
 
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  • #2
with 120 points you could take the mean and deviation of each cluster.
 
  • #3
Don't you have more than one variable: voltage, drop size, and charge? Then you derive a probability plot of drop charge, from which you extract the peak separation? What is frequency; do you mean probability or Hz? FYI: When I did the experiment, I got a value of 0.8 x 10-19 Coulombs.

Bob S
 

1. What is the purpose of the Millikan Experiment?

The Millikan Experiment was designed to accurately measure the charge of an electron, a fundamental constant in physics. This experiment was crucial in confirming the existence of electrons and their charge, as well as determining the value of the charge.

2. How is the Millikan Experiment set up?

The experiment involved suspending tiny oil droplets in an electric field and measuring their motion. The oil droplets were sprayed into a chamber and allowed to fall through a small hole in the top plate, where they were exposed to X-rays. The X-rays caused the droplets to become electrically charged, and by adjusting the strength of the electric field, the droplets could be suspended in mid-air.

3. What are some potential sources of error in the Millikan Experiment?

One potential source of error is the size of the oil droplets, as they may not be perfectly spherical and may have varying densities. Another source of error is air currents in the chamber, which can affect the motion of the droplets. Additionally, variations in the strength of the electric field and the X-ray intensity can also introduce errors in the measurements.

4. How did Millikan account for these sources of error?

Millikan conducted the experiment multiple times and took measurements at different electric field strengths to minimize the effects of errors. He also used multiple droplets of different sizes to account for variations in droplet density. In addition, he made sure to control for air currents and calibrated his equipment regularly.

5. What is the significance of the Millikan Experiment in modern science?

The Millikan Experiment is considered one of the most important experiments in modern physics, as it provided the first accurate measurement of the charge of an electron. This experiment also confirmed the existence of subatomic particles and paved the way for further research and advancements in our understanding of the atom and its components.

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