PHYS 214 Photoelectric Effect Laboratory (Online version)
Name ___Pallavi Das______________________________
Note: we recommend you type in this document for most of your answers. If you need to
include a drawing or equations (and don’t want to use Word equation features), just write on a
sheet of paper, take a photo, and insert the photo to this file. Then upload this Word file on
Canvas. The due date for the laboratory is 6 pm on Friday.
For Activity 1, we will be using the photoelectric simulation at
https://phet.colorado.edu/en/simulation/legacy/photoelectric. This simulation runs on Java,
which many computers will not run anymore (at least now without some effort), so we have
made videos of the simulation and/or collected the data from the simulation for you. But you
are most welcome to run the simulation for yourself if you can (run it at 100% Intensity if you
do). For Activity 2, we will use experimental data collected by a TA.
See lecture 9 and/or the relevant section of the textbook for details about the photoelectric
effect.
You will want to have open the Excel file of data posted on Canvas on the Laboratories page.
Note: we encourage you to use Excel (or a similar spreadsheet program) for analyzing your data
and that you use the trend line function for x-y scatter plots.
Activity 1. Simulation
Watch this video of the simulation with Platinum as the target. Use this video (or the simulation
itself) to collect your data. In the simulation, we can control the wavelength of the light and the
voltage applied (in 0.2 V increments) and we can measure the photocurrent.
As you watch the video, answer these questions/do these tasks (1 and 2 below):
1. What is approximately the longest wavelength for which one observes a photocurrent? Why
is there no photocurrent for longer wavelengths than this? What quantity does this wavelength
tell you about Platinum?
The longest for which one observes a photocurrent is around the value of 185 nm. There is
absence of photocurrent for wavelengths longer than this because the threshold energy for the
UV light is higher than the energy emitted by the wavelengths and hence is unable to let
conductors eject electron from their surface. This quantity tells that the Platinum has a very
high work function (or in other words it is almost inert and is basically non-reactive element.)