Conservation of angular momentum

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Discussion Overview

The discussion revolves around the polarization of scattered radiation when incident radiation is linearly polarized, particularly in the context of scattering by different materials, such as lossless dielectrics and conducting materials. The implications for conservation of angular momentum in these scenarios are also considered.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions whether scattered radiation can be circularly or elliptically polarized when the incident radiation is linearly polarized, particularly in the case of scattering by a conducting material.
  • Another participant notes that scattering can involve the material gaining or losing angular momentum, and that angular momentum can be derived from the photon's position and velocity, in addition to its intrinsic angular momentum.
  • A third participant seeks clarification on whether a linearly polarized electromagnetic wave scattered by a fixed spherical perfect conductor can result in elliptically polarized radiation.
  • One participant expresses an expectation that elliptically polarized scattering may occur in general cases, particularly at certain scattering angles, but admits uncertainty.

Areas of Agreement / Disagreement

Participants express differing views on the outcomes of scattering in relation to polarization and conservation of angular momentum, indicating that multiple competing perspectives remain without consensus.

Contextual Notes

The discussion does not resolve the assumptions regarding the conditions of scattering, such as the specific properties of the materials involved or the angles of scattering.

rays
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If the incident radiation is linearly polarized can the scattered radiation be circularly or elliptically polarized? If the scatter is a lossless dielectric the scattered radiation is not elliptically polarized. How about if the scatter is conducting? if the scattered radiation is elliptically polarized, does it violate the conservation of angular momentum?

Many thanks!
 
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Scattering where?
In general, the material can get (or lose) angular momentum. In addition, angular momentum in some specific frame can come from the position of the photon itself (together with the velocity), its intrinsic angular momentum is just one component.
 
mfb,

Thank you for the quick reply!

In classical eletromagnetic theory, if the incident EM wave is linearly polarized (no angular momentum) and it is scattered by a fixed spherical perfect conductor, then can the scattered EM wave be elliptically polarized?

rays
 
I would expect this in the general case (at least for some scattering angles), but I don't know.
 

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