Exploring Light Intensity Through Polarizers
Explore light intensity through linear polarizers at angles from 0° to 90°. Measure transmitted light with lOLab sensor, test repeatability with two trials per angle, and analyze results using Malus' Law.
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Physics 102 Lab 7
Introduction:
The goal of this lab is to explore the intensity of light that is transmitted through a pair of linear
polarizers as a function of the angle between the transmission axes. W e will measure this through
the lOLab device by utilizing the light feature and measuring ten evenly spaced angles between
03 to 90 3 for the transmission axes. By making two measurements for each angle, we will be able
to test the repeatability for both our angle and intensity measurements. An important concept
introduced in this lab is Mains' Law, as it helps us to study the light intensity of a
polarizer-analyzer relationship, which will be helpful in assessing the results of this experiment.
Methods:
1. Place tape on lOLab to create an elevated surface above the light sensor
2. Place the polarized filters directly on top of each other (no angle between)
3. Measure distance of bottom of flashlight to polarized filters (10cm)
4. Record data for 10 seconds using light sensor on lOLab
5. Repeat steps 2-4 for two trials
6. Move polarized filters so that they are at a 10° degree using a protractor
7. Measure distance of bottom of flashlight to polarized filters (10cm)
8. Record data for 10 seconds using light sensor on lOLab
9. Repeat steps 6-8 for two trials
10. Repeat steps 6-8 moving the polarized filter 1 0° more each time until you reach 90° and
recording data for two trials for each angle
Introduction:
The goal of this lab is to explore the intensity of light that is transmitted through a pair of linear
polarizers as a function of the angle between the transmission axes. W e will measure this through
the lOLab device by utilizing the light feature and measuring ten evenly spaced angles between
03 to 90 3 for the transmission axes. By making two measurements for each angle, we will be able
to test the repeatability for both our angle and intensity measurements. An important concept
introduced in this lab is Mains' Law, as it helps us to study the light intensity of a
polarizer-analyzer relationship, which will be helpful in assessing the results of this experiment.
Methods:
1. Place tape on lOLab to create an elevated surface above the light sensor
2. Place the polarized filters directly on top of each other (no angle between)
3. Measure distance of bottom of flashlight to polarized filters (10cm)
4. Record data for 10 seconds using light sensor on lOLab
5. Repeat steps 2-4 for two trials
6. Move polarized filters so that they are at a 10° degree using a protractor
7. Measure distance of bottom of flashlight to polarized filters (10cm)
8. Record data for 10 seconds using light sensor on lOLab
9. Repeat steps 6-8 for two trials
10. Repeat steps 6-8 moving the polarized filter 1 0° more each time until you reach 90° and
recording data for two trials for each angle
Equations Used:
Mallis' Law: 7 = 7 Qcos 6
Where 1= intensity of light after leaving the second polaroid, 7. = intensity of light before
entering the second polaroid. and 6 = the angle between two polaroids.
Note: when measuring the angle 6 it will be where the intensity of the light is 4- of the highest
intensity measured.
Results:
Data table:
background = 0.018
Angle Intensity liner 5tty witti backgroun d subtracted cos A 2(thetai
0 0 644 0.628 1
0 0 668 0 4 5 1
10 0 522 0 504 0 96984631
10 0 KM 0.466 0.96984631
20 0413 0.395 0.88 3022222
20 0 421 0.403 0.883022222
30 0 369 0 351 0.75
30 0 406 0.368 0.75
40 D 292 0.274 0.58 6824089
40 0 282 0 264 0.586824089
50 0216 0.198 0 413175911
50 0 232 0214 0 4 1 3 1 7 5 9 1 1
0 0 0 132 0.114 0 2 5
50 0 134 0 116 0 25
70 0 062 0.044 0.116977778
70 0 06? 0.044 0 116977778
00 0 032 0014 0.03015369
50 0 029 OOH 0 03015369
90 0.02 0 0 0 2 3.7S247E 33
90 0.018 0 3 75247E 33
0 = tmgle=?ncer?ai7£
Mallis' Law: 7 = 7 Qcos 6
Where 1= intensity of light after leaving the second polaroid, 7. = intensity of light before
entering the second polaroid. and 6 = the angle between two polaroids.
Note: when measuring the angle 6 it will be where the intensity of the light is 4- of the highest
intensity measured.
Results:
Data table:
background = 0.018
Angle Intensity liner 5tty witti backgroun d subtracted cos A 2(thetai
0 0 644 0.628 1
0 0 668 0 4 5 1
10 0 522 0 504 0 96984631
10 0 KM 0.466 0.96984631
20 0413 0.395 0.88 3022222
20 0 421 0.403 0.883022222
30 0 369 0 351 0.75
30 0 406 0.368 0.75
40 D 292 0.274 0.58 6824089
40 0 282 0 264 0.586824089
50 0216 0.198 0 413175911
50 0 232 0214 0 4 1 3 1 7 5 9 1 1
0 0 0 132 0.114 0 2 5
50 0 134 0 116 0 25
70 0 062 0.044 0.116977778
70 0 06? 0.044 0 116977778
00 0 032 0014 0.03015369
50 0 029 OOH 0 03015369
90 0.02 0 0 0 2 3.7S247E 33
90 0.018 0 3 75247E 33
0 = tmgle=?ncer?ai7£
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