The vibration direction of light wave

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Discussion Overview

The discussion revolves around the vibration direction of light waves, particularly in the context of classical electromagnetic theory and the nature of sunlight. Participants explore concepts related to polarization, the orientation of electric and magnetic fields, and the behavior of unpolarized light.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants describe light as an oscillating magnetic wave and an oscillating electric wave that are perpendicular to each other, with polarization determining the orientation.
  • There is a question regarding how sunlight, which appears to come from multiple sources, can oscillate in just one direction.
  • One participant mentions that the direction of a photon is defined by the Poynting vector, which involves a cross product of electric and magnetic fields, indicating that both fields are orthogonal to the direction of travel.
  • Another participant clarifies that for unpolarized light, the vibrations of the electric and magnetic fields are random but remain orthogonal to the direction of travel.
  • It is noted that while individual photons have electric and magnetic vibrations that are orthogonal to each other and to the direction of travel, unpolarized light consists of many photons with randomly oriented vibrations.

Areas of Agreement / Disagreement

Participants express various interpretations of how light oscillates and the implications of polarization, with no clear consensus on the implications of sunlight's multiple source appearance or the nature of its vibration direction.

Contextual Notes

Some assumptions about polarization and the behavior of light may not be fully explored, and the discussion includes references to external sources for further clarification.

ltd5241
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If the light move from left to right, what's the vibration direction of light wave? up-down or front-back or some other ways?
 
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well, in a classical picture, light is an oscillating magnetic wave reinforcing an oscillating electric wave (or vice versa) which is perpendicular to it. However, the polarization of light determines its orientation. See http://en.wikipedia.org/wiki/Polarization
 
maverick_starstrider said:
well, in a classical picture, light is an oscillating magnetic wave reinforcing an oscillating electric wave (or vice versa) which is perpendicular to it. However, the polarization of light determines its orientation. See http://en.wikipedia.org/wiki/Polarization

What about the sunlight?
 
I think he means that sunlight appears to come from more than one source spots, so how can it just oscillate in one direction?
 
haloshade said:
I think he means that sunlight appears to come from more than one source spots, so how can it just oscillate in one direction?

I'm not sure what the OP means... as for your interpretation, who claimed sunlight was polarized?
 
water vibrate up-down right? what about the one colour normal light?
 
The direction of a photon (radio wave, microwave, IR radiation, visible light, UV radiation, x-rays, gamma rays, synchrotron radiation, etc.) is given by the Poynting vector, P = E x H.. Since it is a vector cross product. Both E and H are orthogonal to P.
 
  • #10
Bob S said:
The direction of a photon (radio wave, microwave, IR radiation, visible light, UV radiation, x-rays, gamma rays, synchrotron radiation, etc.) is given by the Poynting vector, P = E x H.. Since it is a vector cross product. Both E and H are orthogonal to P.

Do you mean the direction is random and vibrate in all direction which is orthogonal to the light travel direction?
 
  • #11
ltd5241 said:
Do you mean the direction is random and vibrate in all direction which is orthogonal to the light travel direction?
Precisely. For all unpolarized light, the direction of vibrations of the electric and magnetic fields is random, as long as they are orthogonal to the direction of travel. For individual light "photons", the individual quanta of light, the electric and magnetic vibrations are orthogononal to each other, and both are orthogonal to the direction of travel. But light is composed of billions of photons, and for unpolarized light, they are all randomly oriented.
 
  • #12
Bob S said:
Precisely. For all unpolarized light, the direction of vibrations of the electric and magnetic fields is random, as long as they are orthogonal to the direction of travel. For individual light "photons", the individual quanta of light, the electric and magnetic vibrations are orthogononal to each other, and both are orthogonal to the direction of travel. But light is composed of billions of photons, and for unpolarized light, they are all randomly oriented.

That's what i want.And thank you all who answer my question!
 

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