Why light is not considered as a longitudinal wave?

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Discussion Overview

The discussion revolves around why light is not classified as a longitudinal wave, focusing on the properties of light, particularly polarization, and the implications of electromagnetic wave theory. Participants explore theoretical and experimental aspects of wave behavior, particularly in relation to Maxwell's equations.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Experimental/applied

Main Points Raised

  • Some participants assert that light can be polarized, which is a characteristic of transverse waves, and therefore light cannot be a longitudinal wave.
  • Others mention that the amplitude of electromagnetic waves is typically oriented perpendicular to the direction of propagation, supporting the classification of light as a transverse wave.
  • A participant questions the clarity of the explanations provided and seeks further reasons for the classification of light.
  • One participant suggests that longitudinal waves cannot be polarized, reinforcing the argument against light being a longitudinal wave.
  • Another participant introduces the idea that light can exhibit longitudinal polarization in specific contexts, such as in optical fibers, but emphasizes that in a vacuum, Maxwell's equations dictate that light cannot have a longitudinally polarized component.
  • There is a suggestion to refer to the solution of Maxwell's equations to understand the wave nature of light better.

Areas of Agreement / Disagreement

Participants express differing views on the classification of light, particularly regarding polarization. While some agree that polarization is a key reason light is not a longitudinal wave, others introduce exceptions and question the completeness of the explanations. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants reference Maxwell's equations and the mathematical derivation of light's wave equation, indicating that some assumptions or steps in the reasoning may not be fully explored or agreed upon.

Trojan666ru
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I would like see the reasons why light is not considered as a LWave
 
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It can be polarized.
 
Because the quantity described in the amplitude of an electromagnetic wave is typically oriented perpendicular to the direction of propagation in physical space.

There are exceptions (like in plasmas), but that's a special circumstance.
 
Nobody is clear in their answers.
I would like to hear the reasons
It can be polarised! What?
 
I don't know how much more clear I can be. Longitudinal waves cannot be polarized. Light can be polarized. Therefore light cannot be a longitudinal wave.
 
How do we find that light can be polarized? Any experiment?
 
DaleSpam said:
I don't know how much more clear I can be. Longitudinal waves cannot be polarized. Light can be polarized. Therefore light cannot be a longitudinal wave.

Is that the only reason why light is considered as a traverse wave?
 
Pythagorean gave another reason, and there are most likely still other reasons. All the reasons are equivalent mathematically, but to me the polarization is the one that seems most clear.
 
Trojan666ru said:
How do we find that light can be polarized? Any experiment?
Sure, take two polarizing filters (e.g. lenses from sunglasses), make light pass through both, and rotate them relative to each other to see light be blocked completely or pass.
 
  • #10
Light can be polarised longitudinally! (e.g. in an optical fibre or other waveguide structure).

In a vacuum, however, Maxwell's equations dictate that light cannot have a longitudinally polarised component.

Claude.
 
  • #11
Trojan666ru said:
Nobody is clear in their answers.
I would like to hear the reasons
It can be polarised! What?

This is very confusing, and no one has asked the OP one very obvious question, so I will ask.

Trojan666ru: have you ever solved Maxwell equation to obtain the light's wave equation?

If you haven't, please look at that first and see if that answers your question.

If you have, then what is the issue, considering that the transverse description of light just drops onto your lap when you solve it?

Zz.
 

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