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The Millikan Oil Drop Experiment. Measuring the elementary charge of an electron. Introduction. No one has ever seen an electron. In fact, no one has even seen an atom! So how do we know the charge on the electron? You are about to find out…. The Mission.
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The Millikan Oil Drop Experiment Measuring the elementary charge of an electron
Introduction • No one has ever seen an electron. In fact, no one has even seen an atom! So how do we know the charge on the electron? • You are about to find out…
The Mission Your mission, should you choose to accept it (ha ha, you have to!), is to complete the following tasks: • Find out what the Millikan Oil Drop Experiment is, and some background, such as when it was performed, … • Describe what was involved in the experiment. You must include a diagram of the apparatus and the physics principles behind the experiment. • You then do the experiment and make a conclusion.
Background • Create a file with the name: firstlastname.doc. Answer the following questions in that file, by finding QUALITY sites on the internet. BE SURE TO PROVIDE A LIST OF THE SITES YOU USED. • Q1: Where and when was Robert Millikan born? • Q2: Briefly describe how he became interested in elementary physics. • Q3: What was his earliest major success? • Q4: What was Millikan’s major contribution to the photoelectric effect equation? • Q5: When, and for what, did he win his Nobel Prize?
Millikan’s Oil Drop Experiment • Your task in the experiment is to determine the charge on various charged spheres by balancing the weight of the spheres and the electric force on them: • To perform this experiment, you must record the mass of the spheres and the electric field required to stop each drop. • Balance five drops – ensure that each drop remains stationary for at least 10 seconds. In addition, do not use electric field values above 68kV/m.
Millikan’s Oil Drop …. • Make sure you record this information in a data table. • Describe what was involved in the experiment. You must include a diagram of the apparatus and the physics principles behind the experiment. Explain all of the pertinent mathematical relationships • To perform this experiment, click here. You may wish to click the Replace with new drops box.
Analysis • Using the lowest charge obtained, calculate the ratio of every charge to that lowest charge: your first value is 1.00. • Using Autograph, plot a graph of charge (y – axis) versus ratio (x – axis). Make sure the unit of the charge is • Choose a linear fit. • Save it to be emailed in. • Q5: What does the slope of the graph represent? • Q6: Compare this to the accepted value; calculate the percent difference. • Q7: What is another, more common unit for kV/m? Show how you got this answer. (The ‘k’ means kilo)
Summary • Conclusion: Summarize your findings in paragraph form. • Email me your word document and your graph. The name of the document needs to be “firstlastname.doc” and the graph should be named “firstlastnamegraph.agg. Ex. hansolo.doc or lukeskywalkergraph.agg