Experiment 12: Polarization of Light

Purpose: Observe the change in light intensity of light as it passes through polarized filters.

Materials:

• computer
• light sensor
• LabPro
• Logger Pro
• light source
• polarizing filters
• protractor

Set Up:

Preliminary Questions:
1. When the axis marks are at tight angles to each other, very little light can get through the filters.

2. When they are parallel the intensity is at its maximum.

2 Polarizers Data:

Angle (o)	Intensity Counter Clockwise(lux)	Intensity Clockwise(lux)	Average Intensity (lux)	I/Imax	cos2θ
0	325.517	324.223	324.870	1.000	1.000
15	220.165	236.994	228.579	0.704	0.933
30	174.619	176.575	175.597	0.541	0.750
45	115.546	117.860	116.703	0.359	0.500
60	72.517	74.718	73.618	0.227	0.250
75	51.322	50.376	50.849	0.157	0.067
90	35.165	36.821	35.993	0.111	0.000
105	92.148	91.407	91.777	0.283	0.067
120	164.268	165.100	164.684	0.507	0.250
135	231.547	232.313	231.930	0.714	0.500
150	304.157	305.323	304.740	0.938	0.750
165	317.149	319.576	318.362	0.980	0.933
180	329.157	327.669	328.413	1.011	1.000

Intensity vs. Angle for clockwise motion

Intensity vs. Angle for counterclockwise motion

Average Intensity vs. Angle

Average Intensity vs. Cos^2(theta)

When the polarizers are parallel to one another the intensity is at the minimum. When they are parallel, the intensity is at a maximum.

3 Polarizers Data:

When the second polarizer is at 0 or rotated 90 degrees, then it become perpendicular to both the first and third polarizers which results in minimal intensity. When the second polarizer is rotated 45 degrees, then half of the light from the first polarizer makes it through the filter. That in turn gets passed through the third filter at half the intensity which is the highest intensity this apparatus can reach.

Polarization upon Reflection:

1. No, the fluorescent bulb does not have polarization to it.

2.Yes, the reflected light does have polarization. It is polarized in the plane perpendicular to the table because when we turn the filter parallel to the table, no light passes through the filter.

Conclusion: The labs results are consistent with the calculations.