Understanding Brewster Angle & Polarised Beams

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Discussion Overview

The discussion centers around the Brewster angle and its relation to polarized beams, exploring the underlying electromagnetic theory and practical applications. Participants express varying levels of understanding and seek clarification on the topic.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant expresses confusion about the Brewster angle and its connection to polarized beams, questioning the necessity of electromagnetic theory for understanding.
  • Another participant suggests that while electromagnetic theory is necessary for understanding, it may not be needed for application, asking for clarification on the specific information sought.
  • A request for an electromagnetic explanation of the Brewster angle is made by a participant.
  • One participant admits to not knowing the electromagnetic explanation and suggests looking at Wikipedia, indicating that the topic may not be straightforward.
  • A participant mentions the Fresnel equations, explaining their relevance to the Brewster angle and how they describe the interaction of electromagnetic waves at media interfaces.
  • It is noted that at the Brewster angle, the reflected portion of the electric field is zero for parallel polarization, leading to the reflection being polarized perpendicular to the interface.
  • Another participant expresses the need to read about the Fresnel formula for better understanding.
  • A participant offers a Python program to calculate reflection coefficients for different angles of incidence, inviting others to request it.
  • There is a repeated mention of difficulty finding the relevant Wikipedia article on the topic.
  • A participant requests specific references from the Wikipedia article regarding the polarization of the reflected beam.
  • Another participant asserts that the Wikipedia article contains multiple relevant sections and figures that explain the polarization phenomenon.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the understanding of the Brewster angle and its implications for polarized beams. There are multiple viewpoints regarding the necessity of electromagnetic theory and the clarity of available resources.

Contextual Notes

Some participants express uncertainty about their knowledge of the Fresnel equations, which may limit their understanding of the Brewster angle. There are also references to external resources, such as Wikipedia, that may not be universally accessible or clear to all participants.

kame
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Hi! I didn't understand how the brewster angle works. Why do I have a polarised beam? Do I need electromagnetism to understand this?
 
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To understand why this happens you need electromagnetic theory. But to apply the concept you don't. What exactly are you looking for in an answer here?
 
I need the electromagnetic explanation :)

Thanks in advance
 
I can't answer that for you, I don't know it. You'd do best to look at wikipedia at this point. I also don't think that this is going to be cut and dry.
 
Wikipedia? I didn't find it. :(
 
I'm assuming you have some knowledge of the fresnel equations, which deal with how an electromagnetic wave interacts with the interface between two media. If you don't know this, then it is much more difficult to accurately describe the Brewster angle!

Any ways, from the fresnel equations it is easy to see when the reflected portion of the electric field is zero. Trivially, there is the case where n1=n2, that is, the two media are optically identical and of course there is no reflection. The second case is the brewster angle, for which [tex]n_2 / n_1 = tan \theta_B[/tex]. Another way of thinking about this is that if you have a beam which is a mixture of polarizations parallel to and perpendicular to the interface, the reflected portion of the beam parallel is completely zero, i.e. the reflection is polarized perpendicular to the interface. Equivalently, if you shine a beam which is parallel polarized on the interface, there will be no reflected beam at all!

Does that help at all? If what I've said doesn't make sense I suggest you look back at the Fresnel equations and perhaps read the wiki article and see if you still have any questions =)
 
I have to read about the fresnel formula. Thanks!
 
If you run python I have a little program that will take 2 refractive indices and spit out the reflection coefficients for each angle of incidence from 0-90. Let me know if you want it.
 
kame said:
Wikipedia? I didn't find it. :(

That's surprising, since they have an entry on it.
 
  • #10
@dacruick I love Python! Please send me the file.
This is my Python-Blog :) kkaammee.blogspot.com/
 
  • #11
@Vanadium50
Can you show me where they write why the reflected beam is polarised?
 
  • #12
That would be the first paragraph. And the second, third, fouth, fifth, sixth seventh and last. And the first and last figure.

The advice to look at the Wikipedia article was a good one. Really.
 

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