Teaching Modern Physics - QuarkNet - Fermilab

Modern Physics
Photoelectric Effect Write-up
Your lab write-up should be somewhat formal, be typed, and stand on its own and not rely on
someone else’s work; include printouts of all graphs and data tables. If you would like to
organize it into sections (i.e., Purpose, Procedure, Data . . .), you may, but you are not required
to. Either way, you need to provide detailed answers to the following questions in addition to
providing your data in tables and your graphs. Another reasonably intelligent person (i.e., your
roommate) should be able to pick up the report and be able to replicate your particular
experiment and get the same kinds of data you did.
1. What was Planck’s assumption and why was Planck important?
2. Provide a sketch and short description of the experimental setup. Why is it necessary to do
this experiment in the dark?
3. Give a short description of what is happening inside the “Photoelectric Effect” box. Include
what happens when you twiddle the two knobs.
4. Describe what you do to get a graph of current vs. voltage and why these graphs are
important.
5. What is the final goal of the experiment? What calculations do you need to do to get there?
Provide at least a sample of each calculation that you did.
6. What is your final graphical model of kinetic energy vs. frequency? Explain the graph and
the mathematical model you use to fit the data. Explain what the slope and y-intercept mean
and the units of such numbers.
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