Names:__________________________________________________ Group:_______________
Optics Lab: Reflection, Refraction, Polarization and Thin Lenses
DATA
Part 1: Snell’s Law
How can you confirm the disk is set up correctly?
Angle of Incidence
Angle of Refraction (CW) ±
Angle of Refraction (CCW) ±
0⁰
10⁰
20⁰
30⁰
40⁰
50⁰
60⁰
70⁰
80⁰
What difficulties did you encounter in measuring the angle of refraction of large angles of
incidence?
Part 2: Internal Reflection
Record any changes in the reflected and transmitted ray as you increase the angle of incidence.
Record the critical angle from the clockwise and counterclockwise directions:
θCW = ____________± ______________
θCCW = ___________± ______________
Part 3: Brewster’s Angle
Record Brewster’s angle from the clockwise and counterclockwise directions:
θCW = ___________± ______________
θCCW = ___________± ______________
Is the reflected light plane polarized? If so, at what angle from the vertical is the plane of
polarization? Was the light still plane polarized when not at Brewster’s angle?
DATA ANALYSIS
Part 1: Snell’s Law
Attach plots for Snell’s Law and index of refraction. Remember to clearly label the graphs and
include linear fits. Are your graphs consistent with Snell’s Law? Explain.
For Part 1, you encountered difficulties measuring the angle of refraction at large angles of
incidence. How would you take this into account in the analysis of your data?
Report the index of refraction from each of these graphs.
nCW=___________± ______________
nCCW=___________± ______________
Calculate the weighted average (show your work):
n=___________± ______________
Part 2: Internal Reflection
Calculate the index of refraction (show your work):
n=___________± ______________
Part 3: Brewster’s Angle
Calculate the index of refraction (show your work):
n=___________± ______________
Discussion Questions
Compare your results for the index of refraction with the value of 1.49 for acrylic. Which of
your measurements is the most precise? Which is the most accurate?
What is the largest source of error in the experiment? How would you improve the experiment
in the future?
Lab: Thin Lenses
Part 1 Data: Ray Tracing – any general comments?
Part 2: Optic Bench Work
Convex lens:
p
up
q
uq
Qualitatively describe what happens when p approaches f.
What effects does the BLUE filter have on your image? Is the image sharper with or without
the filter? Does the image distance increase or decrease?
What effects does the RED filter have on your image? Is the image sharper with or without the
filter? Does the image distance increase or decrease?
Analysis
Calculate f for each pair of measurements in the table. Find the average and calculate the
standard error.
Discussion Questions
Summarize your diagram from part 1 – when do you have a virtual image? When does this
occur in the real world?
How accurately are you able to determine f in part 2? How can you determine f quickly for any
lens if you don’t have a light table setup and the lens isn’t labeled?
Based on observations made in part 2, what can you conclude about the dependence of the
index of refraction on the frequency of light? Does n increase or decrease with increasing
frequency?
What kinds of lenses are used in eyeglasses? Why?
Can you use the simulation linked in the lab writeup to build a microscope or a telescope?
What designs/arrangements work best to magnify?
How would you improve these labs?