Experiment 12: Polarization of Light

Introduction: The purpose of this experiment was to observe the change in light intensity of light passing through crossed polarizing filters and measuring the transmission of light through two polarizing filters as a function of the angle between their axes.

Preliminary Questions:

1) The view gradually fades and returns depending on the angle of the polarizer relative to the light incoming.

2) When the axes are parallel, the light intensity is at a maximum.

Data:

Example of measurement of light passing through the polarizers and measuring light intensity.

Setup of apparatus used in this experiment.

Another example of how measurements were taken.

Another view of the lab setup.

A third polarizer was added perpendicular to the first polarizer.

     Two polarizers:

Angle (degree)	Intensity (clockwise) (lux)	Intensity (counterclockwise) (lux)	Average (degree)	I/Imax	cos(theta)^2
0	204	208	206	1	1
10	201	198	199.5	0.968447	0.969846
20	189	182	185.5	0.900485	0.883022
30	172	163	167.5	0.813107	0.75
40	150	146	148	0.718447	0.586824
50	115	113	114	0.553398	0.413176
60	97	87	92	0.446602	0.25
70	83	75	79	0.383495	0.116978
80	67	63	65	0.315534	0.030154
90	59	57	58	0.281553	3.75E-33

           When the polarizers are perpendicular to each other, the amount of light that passed through the filter was minimal. When the polarizers are parallel to each other, the amount of light that passed through the filer was at a maximum.

     Three polarizers:

Angle (degree)	intensity (clockwise) (lux)	cos^2
0	50	1
10	49	0.969846
20	52	0.883022
30	58	0.75
40	62	0.586824
50	62	0.413176
60	58	0.25
70	54	0.116978
80	50	0.030154
90	48	3.75E-33

  

      When the second polarizer is at its 0 and 90 degree positions, the second polarizer is perpendicular to the either the first or third polarizer. The experiment is then similar to the perpendicular position in two polarizers. There is no light through the filter, so the intensity is at a minimum.
      When the second polarizer is at a 45 degree position, half of the light from the first filter goes through the second polarizer, and half of the light from the second filter goes through the third polarizer. Thus, the intensity is at a maximum.

Polarization upon reflection

Question 1: Does the light from the fluorescent bulb have any polarization to it? If so, in what plane is the light polarized? How can you tell?

No, the light from the fluorescent bulb does not have any polarization to it.

Question 2: Does the reflected light have an polarization to it? If so, in what plane is the light polarized? How can you tell?

Yes, the reflected light does have polarization to it. The light is polarized in the plane perpendicular to the table. When the polarizer was used to test the light, it has the most apparent change when it is parallel to the table.


Conclusion: The data measured in this experiment was consistent with the theoretical values.