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Problem: What is the relationship between how much light passes through a Polaroid filter and the angle the filter is rotated?


Materials: One Polaroid filter, one set of Polaroid glasses, photocell, light source, protractor, ring stand, various clamps.



1) Begin by investigating some of the properties of light. Look at a your lab table and observe how light reflects off of it.

2) Look through the single Polaroid filter at a light bulb. Rotate the filter. Observe and record any changes in your lab notebook.

3) Look at the light reflected off your lab table or any shiny surface. Now look at the same light through the Polaroid filter. Rotate the filter slowly. Continue to rotate a complete 360 degrees.

4) Discuss what you observe with your lab group.

5) Set up your experiment as shown in Figure 1.

6) Copy Table I into your lab notebook.

7) Turn on the light source.

8) Set the protractor to 0 degrees and record the intensity of light passing through both filters. Record the value in Table I.

9) Turn the filter 20 degrees and measure the light intensity. Record your value. Continue until you have completed 180 degrees.




Table I.


Angle Light Intensity







Graph: Plot the angle (degrees) on the x-axis and the intensity (milliamps) on the y-axis.




1) What are the independent and dependent variables?

2) How are the variables changing with relationship to each other?

3) What happens to the dependent variable when the independent variable increases? decreases?

4) How does the relationship shown in this experiment compare with other relationships you have so far seen?

5) How does the equation for this relationship compare with those of other equations you have studied?



1) Why are Polaroid glasses recommended for people driving cars? Where else would Polaroid filters come in handy?




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