How Does Malus' Law Explain Light Transmission Through Polarizers?

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SUMMARY

This discussion centers on the application of Malus' Law to determine the initial polarization direction of light passing through two polarizers oriented at 35.7 degrees to each other, resulting in only 11.9% of the light being transmitted. Malus' Law states that the transmitted intensity (I) is calculated using the formula I = Iincident * cos²(θ), where θ is the angle between the incident light's polarization direction and the polarizer's axis. Additionally, the discussion touches on calculating the width of the first-order spectrum from a grating with 7770 lines/cm when white light with wavelengths from 391 nm to 758 nm is used, projected onto a screen 2.40 m away.

PREREQUISITES
  • Understanding of Malus' Law and its formula: I = Iincident * cos²(θ)
  • Basic knowledge of light polarization and polarizers
  • Familiarity with diffraction gratings and their properties
  • Ability to perform calculations involving angles and light intensity
NEXT STEPS
  • Study the derivation and applications of Malus' Law in optics
  • Learn how to calculate the width of spectra produced by diffraction gratings
  • Explore online resources for practical examples of light polarization
  • Review the principles of light intensity and its relationship with angle in polarizing filters
USEFUL FOR

Students studying optics, physics enthusiasts, and educators looking to deepen their understanding of light behavior through polarizers and diffraction gratings.

Evergreen
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need help with capa questions...

Two polarizers are oriented at 35.7o to each other and plane-polarized light is incident on them. If only 11.9 percent of the light gets through both of them, what was the initial polarization direction of the incident light?


White light containing wavelengths from 391 nm to 758 nm falls on a grating with 7770 lines/ cm. How wide is the first-order spectrum on a screen 2.40 m away?




just two questions, i have no clue... :redface:
 
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Evergreen said:
Two polarizers are oriented at 35.7o to each other and plane-polarized light is incident on them. If only 11.9 percent of the light gets through both of them, what was the initial polarization direction of the incident light?
Are you familiar with Malus' Law? It says that if linearly polarized light passes through a polarizer, the intensity of the light transmitted is I = Iincidentcos2(θ), where θ is the angle between the polarization direction of the incident light and the polarization axis (transmission axis) of the polarizer.
White light containing wavelengths from 391 nm to 758 nm falls on a grating with 7770 lines/ cm. How wide is the first-order spectrum on a screen 2.40 m away?
Take a peek at these threads:
https://www.physicsforums.com/showthread.php?t=16902
https://www.physicsforums.com/showthread.php?t=17047
 
i need a numeric answer, for the second question that I am posting, i did use a similar method, but my answer is still wrong
 
Evergreen said:
i need a numeric answer, for the second question that I am posting, i did use a similar method, but my answer is still wrong
Show your work and I'll take a look.
 
Last edited:
Doc Al said:
Are you familiar with Malus' Law? It says that if linearly polarized light passes through a polarizer, the intensity of the light transmitted is I = Iincidentcos2(θ), where θ is the angle between the polarization direction of the incident light and the polarization axis (transmission axis) of the polarizer.
QUOTE]
I have a question on this also...
I am fairly new with this material, and I know that I am trying to find theta, but what do I plug in for I and Io? Is there any good reading online for this?
 
Law of Malus

PrettyMz4Christ said:
I have a question on this also...
I am fairly new with this material, and I know that I am trying to find theta, but what do I plug in for I and Io?
That depends on what you are given in the problem. If you have a specific problem, post it and your work and I'll take a look. (You might want to start a new thread.)

I give a brief description of Malus' law in my earlier post.
Is there any good reading online for this?
Do a search on Malus' Law and you'll find plenty. Here's one place to start: http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/polcross.html#c3

Welcome to PF!
 

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