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I'm not understanding what an unpolarized wave is. Does that mean there is no electric/magnetic field, or that the field is constant, i.e. frequency = 0? How can that be possible?

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marked as duplicate by Emilio Pisanty electromagnetism Apr 27 '18 at 9:13

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Polarized light gets defined as the light waves that have vibrations occurring within them in a single plane. On the other hand, unpolarized light gets defined as the light waves that have vibrations occurring within them at random angles without any plane.The phase difference does not exist, and the changes in the electric field take place at random speeds.The amplitudes of vibrations are equaL.

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Unpolarised light consists of components of polarized in all possible directions perpendicular to the direction of propagation of the wave.Unpolarized light consists of a mixture of light with different polarizations. If the light is traveling in the positive x-direction, this means that there are multiple directions in the yz-plane for the electric field oscillations of the various modes comprising the light. Each of these polarization directions can be resolved into components along two mutually perpendicular directions. Thus, an unpolarised beam can be thought of as two plane polarized beams of equal magnitude perpendicular to one another. This give rise to the commonly used pictorial representation of unpolarised light wave shown in figure above.

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  • $\begingroup$ So basically, are you saying that one specific line of propagation has multiple different direction of electric field polarization, or are you saying that it is simply a mix of ellipse/circular/linearly polarized waves? I was confused by the diagram $\endgroup$ – Goldname Apr 27 '18 at 1:21
  • $\begingroup$ Unpolarized light, in general, consists of polarized components in all directions perpendicular to the direction of propagation of the wave. $\endgroup$ – Abhinav Apr 27 '18 at 2:11
  • $\begingroup$ Again, I'm not understanding what you mean by "polarized components in all directions" Does one particular line of propagation have all directions or is it just a mix of linearly polarized waves in different directions? $\endgroup$ – Goldname Apr 27 '18 at 3:02
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    $\begingroup$ Problem is that a superposition of "two plane polarized beams of equal magnitude perpendicular to one another" would be linearly polarized at 45 degrees. The word you use is "mixture", which may describe the rapid random fluctuations of the electric field direction in an unpolarized beam, but one needs to be explicit about that. $\endgroup$ – Pieter Apr 27 '18 at 5:40
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    $\begingroup$ Unpolarized light has, in any time interval substantially shorter than the period of oscillation of the light, a definite E-field direction. However, the direction of the E-field changes rapidly and very rapidly, on the order of tens to hundreds of femtoseconds. Polarization direction corresponds to the direction of the E-field. When the polarization of "randomly polarized" light is measured over reasonable timescales, it averages to zero. $\endgroup$ – S. McGrew Apr 27 '18 at 14:28

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