Why does the free end refraction occur after Brewster's angle in TM?

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Discussion Overview

The discussion centers on the phenomenon of free end refraction occurring after the Brewster angle in transverse magnetic (TM) waves, particularly in the context of light transitioning from vacuum to a denser medium like glass. Participants explore the underlying mechanisms and implications of this behavior from both macro and microscale perspectives.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the terminology "free end" and seeks clarification on its meaning in the context of TM wave behavior at angles greater than the Brewster angle.
  • Another participant explains that at angles greater than the Brewster angle, the reflected wave experiences a 180-degree phase shift, while at angles less than the Brewster angle, it does not, leading to potential cancellation between incident and reflected waves.
  • A different viewpoint suggests that the reflection coefficient can be modeled as a combination of free end and fixed end reflection terms, with the dominance of the free end reflection term at angles greater than the Brewster angle resulting in a positive overall reflection value.
  • One participant expresses understanding and agrees that cancellation occurs when both the incident and reflected beams are observed by a detector at angles exceeding the Brewster angle.

Areas of Agreement / Disagreement

Participants express differing levels of understanding regarding the term "free end" and its implications. There is a general agreement on the occurrence of phase shifts and potential cancellations, but the discussion remains unresolved regarding the precise mechanisms and interpretations of these phenomena.

Contextual Notes

Participants have not fully defined the term "free end," which may lead to varying interpretations of the discussion. Additionally, the mathematical representation of reflection coefficients and the conditions under which cancellation occurs are not fully resolved.

jojoe
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Thanks for reading my question, and i’m really sorry about my poor english.

What i am wondering about is
why does the free end occur after the incidence angle overcome the Brewster angle in TM wave? (The ray incident from vacuum to glass(dense medium))

i tried to interpret this phenomenon with dipole oscillation of medium and the velocity difference of light in different medium(with more detail, vacuum to dense medium), but those trial didn’t make any effective conclusions.

Could someone help me about understanding this with macro or microscale aspect?
 
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Sorry Jojoe, can you try to find another word for free end as I cannot understand it.
At angles greater than the Brewster Angle, the reflected wave undergoes a 180 deg phase shift. At angles less than the Brewster Angle it does not. This phase shift at large angles of incidence can result in cancellation between incident and reflected waves.
 
tech99 said:
Sorry Jojoe, can you try to find another word for free end as I cannot understand it.
At angles greater than the Brewster Angle, the reflected wave undergoes a 180 deg phase shift. At angles less than the Brewster Angle it does not. This phase shift at large angles of incidence can result in cancellation between incident and reflected waves.
I think free end reflection might be proper representation, that the reflected light has the same phase with incident light. I thought about some idea that the reflection coefficient can be represented with the summation of free end reflection term(which has positive sign with cosine) and fixed end reflection term(which has negative sign of sine in sqrt). As the angle gets greater than Brewster angle, the free end reflection term is dominant, so the whole reflection terms gets positive value, which designates free end reflection of TM wave. Will it be related with the cancellation between the incident and reflected waves?
 

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Thank you, I understand now. I think you are correct. Cancellation occurs if the detector sees both the incident beam of light and the reflected beam of light for the case when angle of incidence is greater than the Brerwster Angle.
 

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