Three polarizers homework question

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In summary, by adding a third polarizer with an angle of θ = 71° between two polarizers with perpendicular axes of polarization, some light is able to pass through the combination, resulting in a light intensity of 0.5I(nought)*cos^2(71°)*cos^2(19°). This may not match the expected result due to potential errors in calculating the angles or using incorrect values for the initial light intensity.
  • #1
Sir_Pogo
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Polarizers 1 and 3 have their axes of polarization, indicated by the black solid lines, perpendicular to each other. If you try to shine light through only the combination of 1 and 3, you will find that none passes through. However, now we put in another polarizer (number 2 in the figure) between number 1 and number 3. This polarizer has an axes of polarization that has an angle of θ = 71° with respect to the polarization axes of polarizer 1. Surprisingly, now some light passes through the combination 1+2+3. What percentage of the initial (unpolarized) light intensity passes through?


The light passing through the
first polarizer should be 0.5I(nought). The light passing
through the second polarizer should be
0.5I(nought)*cos^2(angle given). The light passing through
the third polarizer should be the previous answer times
cos^2(angle between axes 2 and 3...)

My answer is not coming out right...Any suggestions of what
I may be doing wrong?
 
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  • #2
Are you using 71 degrees for the first angle and 90-71 degrees for the second angle?
 

1. What is the purpose of this homework question?

The purpose of this homework question is to test your understanding of the properties and behavior of polarizers, specifically when three polarizers are stacked on top of each other.

2. How do polarizers work?

Polarizers are optical filters that only allow light waves vibrating in a specific direction to pass through. They achieve this by using a material with aligned molecules that block one orientation of light waves.

3. Why do the intensity of light change when multiple polarizers are stacked?

The intensity of light changes when multiple polarizers are stacked because each polarizer reduces the amount of light that can pass through it. When multiple polarizers are stacked, the amount of light that can pass through decreases exponentially.

4. What is the Malus' law and how does it apply to this question?

Malus' law states that the intensity of light passing through two polarizers is equal to the cosine squared of the angle between their polarizing axes. In this homework question, Malus' law can be used to calculate the intensity of light passing through three polarizers at different angles.

5. How do I approach solving this homework question?

To solve this homework question, you should begin by understanding the properties and behavior of polarizers. Then, use Malus' law and the given information to calculate the intensity of light passing through each polarizer at different angles. Finally, use the calculated values to determine the overall intensity of light passing through all three polarizers.

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