Does Unpolarized Light Cancel Out Due to Mixed Angles?

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SUMMARY

The discussion centers on the behavior of unpolarized light and its interaction with polarization. It is established that unpolarized light, which consists of electric field vectors oriented randomly, does not cancel out due to the nature of light intensity, which is proportional to the square of the electric field vector's magnitude. This means that even with mixed angles, the resultant intensity increases rather than decreases, as the average total field vector grows by a factor of sqrt(2). The implications of polarized light are also noted, emphasizing that if natural light were polarized, it could lead to zero light in certain configurations.

PREREQUISITES
  • Understanding of basic optics concepts, particularly polarization.
  • Familiarity with electric field vectors and their properties.
  • Knowledge of light intensity calculations and their relationship to electric fields.
  • Basic grasp of interference patterns in light.
NEXT STEPS
  • Research the principles of light polarization and its effects on intensity.
  • Study the mathematical relationship between electric field vectors and light intensity.
  • Explore the concept of interference in polarized light using tools like MATLAB or Python for simulations.
  • Investigate real-world applications of polarized light in optics and photography.
USEFUL FOR

This discussion is beneficial for students of optics, physics enthusiasts, and anyone interested in understanding the principles of light behavior, particularly in relation to polarization and intensity calculations.

Kidphysics
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Homework Statement



Hello, I am reading an intro book on optics and it is discussing the polarization of light and unpolarized light. My question is with unpolarized light I quote:

"This sinusoidally varying electric field can be thought of as a length of rope held by two children at opposite ends. The children begin to displace the ends in such a way that the rope moves in a plane, either up and down, left and right, or at any angle in between."

So with this in mind I think well if most light is naturally unpolarized then wouldn't a mix of all of the different angles eventually end up cancelling each other out? I'd like to think of polarized light as coming in two orthogonal basis and then all others combinations of the two, are all polarized light vectors the sum of basis components like force vectors? I'm still beginning so I appreciate the input.


Homework Equations



not sure

The Attempt at a Solution



looked at the wikipedia article and another website which is how I obtained the quote
 
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It's a good question, and the reason the fields don't cancel each other is that light intensity goes as the square of the electric field vector.

And so a randomly varying field vector will produce intensities proportional to the square of the magnitude of the field, irrespective of orientation. And since the direction is random you can't find a second field vector of equal but opposite magnitude source to cancel the first, because on average their total field would increase by sqrt(2) and their intensity double.

If daylight or lamp light were polarized we'd be in big trouble though, since then two oppositely directed field vectors would cancel and give zero light. That's why interference works, and needs polarized light to happen.
 

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