The Millikan Oil Drop Experiment

1
The Millikan Oil Drop Experiment

• Measuring the elementary charge of an electron

2
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

3
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.

4
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 Millikans major contribution to the
  photoelectric effect equation?
• Q5 When, and for what, did he win his Nobel
  Prize?

5
Millikans 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.

6
Millikans 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.

7
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)

8
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