What do polarisation lens block?

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Discussion Overview

The discussion revolves around the nature of polarization in electromagnetic waves, specifically addressing what aspects of the waves are blocked by polarization lenses. Participants explore the relationship between the electric and magnetic fields in polarized light and seek clarification on the mechanics of how polarization filters operate.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant describes electromagnetic waves as being created by an accelerating charge, leading to a changing electric field that induces a magnetic field, and questions whether polarization blocks the electric or magnetic field.
  • Another participant asserts that discussions of light polarization refer specifically to the electric field, noting that polarizing sunglasses block the electric field that does not align with the filter's polarity.
  • A different viewpoint claims that both the electric and magnetic fields are blocked by a vertically oriented polarizing filter, with the electric field oscillating in the vertical plane and the magnetic field in the horizontal plane.
  • One participant suggests a revision to an earlier statement, emphasizing that electromagnetic waves consist of electric and magnetic components rather than separate fields, referencing the Jefimenko equations for clarification.
  • A participant seeks confirmation on their understanding of how horizontally oriented polarizing filters operate, specifically asking if they block light with the electric field oscillating in the horizontal plane while allowing light with the electric field in the vertical plane to pass through.

Areas of Agreement / Disagreement

Participants express differing views on whether polarization blocks the electric field, the magnetic field, or both, indicating that there is no consensus on the specifics of how polarization filters interact with electromagnetic waves.

Contextual Notes

Some statements reflect differing interpretations of electromagnetic theory, particularly regarding the nature of electric and magnetic fields and their components in the context of polarization.

TT0
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Electromagnetic waves are created by a accelerating charge that induces a changing electric field, that induces a changing magnetic field which propagates together through space. The electric and magnetic field are at right angles to each other. Polarisation blocks all but one plane of the transverse wave. Does it block the electric or magnetic field? Or is the transverse wave of light caused by the wave nature of the direction the propagation of the 2 fields (so it is perpendicular to both electric and magnetic fields at all times)? Or am I misunderstanding something?

Thanks
 
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TT0 said:
Does it block the electric or magnetic field?

when we talk about light and its polarisation, we are always referring to the electric field
So, for example, your polarising sunglasses block the electric field that doesn't align with the
polarity of the polarising filter
 
TT0 said:
Does it block the electric or magnetic field?
Both. A vertically oriented polarizing filter blocks light in which the electrical field is oscillating in the vertical plane and the magnetic field is oscillating in the horizontal plane.
 
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The first sentence in #1 should stop earlier and read:

"Electromagnetic waves are created by a accelerating charge that induces a changing electromagnetic field."

The causal and local sources of the electromagnetic field (there is not an electric and a magnetic field but only electric and magnetic components of the electromagnetic field, depending on the frame of reference they refer to) is the charge-current distribution, as is clearly shown by the Jefimenko equations:

https://en.wikipedia.org/wiki/Jefimenko's_equations
 
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Nugatory said:
Both. A vertically oriented polarizing filter blocks light in which the electrical field is oscillating in the vertical plane and the magnetic field is oscillating in the horizontal plane.

I see, just to check my understanding, does that mean a horizontally orientated polarising filter blocks light in which the electrical field is oscillating in the horizontal plane and the magnetic field is oscillating in the vertical plane but not light in which the electrical field is oscillating in the vertical plane and the magnetic field is oscillating in the horizontal plane?

Thanks a lot
 

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