Experiment: Polarization of Light

The purpose of this lab was to observe the change in the light intensity passing through polarizing filters and to measure the transmission of light through two polarizing filters as a function between their axes.

Equipment:
-Logger Pro
-Light Sensor
-Light beam source
-Polarizing filters
-Protractor

Preliminary Questions:
1. When I placed one polarizing filter on top of the second at right angles to each other, no light passed through the orthogonal filters.

2. When we rotated the filters to that their axis were 180 degrees, most of the light passed through the filters. As we changed the angle of rotation towards 90 degrees, less and less light was transmitted through the filters.

Part One:
We mounted two polarizers lined up bother with the 0 and 180 degree on the polarizer holders on a ruler. We then set up the two polarizers parallel to each other so that the beam source, polarizers, and the viewing points are lined up horizontally. We then turned the second polarizer to the 90 degree mark, while leaving the first polarizer at the 0 degree mark. We then connected the light sensor up to the computer and placed it behind the second polarizer. We then used the file Experiment-31 from the experiment files. We then defined the light level as zero by zero-ing the instrumentation. We then returned the second polarizer to the zero position aligned with the first polarizer. To start the experiment, we then rotated the second polarizer 15 degree clockwise. We then recorded the intensity of the light. We kept turning the polarizer 15 degrees until we rotated it 180 degrees.

Data Analysis:

 

 

 

The shape of these graphs are supposed to be sinusoidal. The show that when the polarizers were orthogonal to each other, the light intensity was at a minimum and when they were parallel to each other, the light intensity was at a maximum.

Part Two:

We then temporarily moved the second polarizer out of the way and put a third polarizer behind the first polarizer so that the light passing through the first and third polarizer is as dim as possible. We then put the second polarizer back in the next to the third polarizer on the opposite side of the first. We adjusted the second polarizer to the 0 degree position. It should appear dark. We then rotated the second polarizer and recorded the intensity every 15 degrees clockwise and counter clockwise. 

Data Analysis:

Polarization Upon Reflection:

1. The light from the flourescent bulb does not have any polarization to it.

2. The reflected light does have polarization to it because a spot on the table goes dark because the light was polarized perpendicular to the table.

Conclusion:

The graphs from the experiment were not perfectly sinusoidal because the room was not perfectly dark and the light from other labs could have interacted with the light intensity that was recorded by the light sensor, but they still show the relationship between the angle of polarization and the light intensity.