Understanding Malus Law and Polaroid Intensity: Conceptual Doubts

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SUMMARY

The discussion centers on Malus's Law, which states that the intensity of polarized light passing through a polarizer is given by the equation I = I0cos2(θ). A participant expresses confusion regarding the expected intensity when θ = 0 degrees, questioning why their textbook states I = I0/2 instead of I = I0. The participant clarifies that I0 represents the intensity after unpolarized light passes through a polarizer, resulting in a 50% reduction in intensity.

PREREQUISITES
  • Understanding of Malus's Law and its mathematical representation.
  • Basic knowledge of light polarization and its effects.
  • Familiarity with the concept of intensity in optics.
  • Ability to interpret diagrams related to optical phenomena.
NEXT STEPS
  • Study the derivation of Malus's Law in detail.
  • Explore the effects of multiple polarizers on light intensity.
  • Investigate the principles of light polarization in various materials.
  • Review the Hyperphysics entry on Malus's Law for visual aids and examples.
USEFUL FOR

Students studying optics, physics educators, and anyone seeking to clarify concepts related to light polarization and intensity calculations.

Suyash Singh

Homework Statement


It is just a conceptual doubt

Homework Equations


According to malus law intensity of light through polaroid is
I=(Io)cos^2(theta) where theta is the angle between axis of polaroid and incident light.

The Attempt at a Solution


But when Theta=0 then I=Io but in my book it is I=Io/2.
why??

and also is my diagram below correct?

--->(light)(I) [](polaroid) --->(I/2) [] --->(I/4) (theta=0 degrees for both polaroid)
 
Physics news on Phys.org
##I_o## is generally taken to be the intensity of the light after an unpolarized source has passed through one polarizer (hence polarizing it). Half of intensity of the source is lost by the first polarization.

Take a look at the diagram for the Law of Malus entry on the Hyperphysics web site:

http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/polcross.html#c1
 
Thankyou :)
 

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