PHY222, Elements of Physics II
Photoelectric Effect, 4 April 2008
Theory Requirements:
- Explain why the photoelectric effect's properties were completely unexpected, when all
physicists had was a theory of light as waves.
- Explain Einstein and Planck's hypothesis, and how it fixed our understanding of the
photoelectric effect.
- State the value we expect to measure for Planck's constant, and how we can measure it
with this experiment.
Comments on the Procedure:
As usual, summarize the major steps in the procedure - make an effort to avoid tangents. Do not
blindly refer to a figure in the lab manual - where appropriate, give a brief description (such as
wire placement, whatever will help you).
Comments on Data:
DESCRIBE THE DATA TABLES and/or GRAPHS YOU PRESENT. This requires barely a sentence to state
what the reader gets to find in each table or graph. Consider it some small evidence that you
have some idea of what you were measuring and recording.
Results Checklist:
- Planck's constant measurement, its uncertainty (from LINEST), and percent difference
compared with the actual Planck's constant.
- Your measurement of the plate's work function (in eV units), and its uncertainty (from
LINEST).
- Sample calculations for converting Planck's constant from eV*s to J*s, and one for
converting wavelength to frequency.
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