Sinusodial solution of EM equation

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Discussion Overview

The discussion revolves around the types of light sources that generate sinusoidally varying electric fields, specifically in the context of electromagnetic (EM) radiation. Participants explore the nature of these fields and the conditions under which they can be described mathematically.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant questions what specific sources of light produce electric fields of the form E(x,t)=E_{o}(x,t) sin(kx−ωt).
  • Another participant asserts that all light sources generate oscillating electric fields, as light is a form of EM radiation.
  • A further contribution explains that oscillating electric fields arise from charged particles oscillating in space, leading to time-delayed electric fields at different distances.
  • Some participants argue that while light sources generate oscillating fields, point sources produce spherical waves, which they claim are not sinusoidal due to their inverse distance dependence.
  • One participant emphasizes the need for clarity in the original question, suggesting that the term "light" should be associated with EM waves rather than static electric fields.
  • A later reply clarifies that to discuss real sources, one must consider a 3D representation of the electric field, noting that an infinite plane wave cannot be produced by any real source.
  • It is mentioned that arbitrary spatial shapes of propagating waves can be expressed as linear sums of plane wave components, similar to how time-varying waves can be described using discrete sinusoidal frequencies.

Areas of Agreement / Disagreement

Participants express differing views on the nature of electric fields generated by light sources, particularly regarding the sinusoidal characteristics of these fields and the implications of point sources versus plane waves. The discussion remains unresolved with competing perspectives on the topic.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the definitions of light and electric fields, as well as the mathematical representation of these fields. The dependence on spatial and temporal variables is also noted but not fully resolved.

pardesi
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what kind of sources of light generate sinusodially varying electric field that is solutions of the form
[tex]E(x,t)=E_{o}(x,t) \sin(kx-\omega t)[/tex]
 
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All light sources do.
 
# Radiation needs "sinusodially varying electric field" For example, if a charged particle makes an oscillation in space, its electric field makes and an oscillation with a delay in time, according to the distance of the field point to the source.
# And light is an EM radiation (which is visible.) So by definition every kind of light sources generate oscillating E fields.
 
ues they do generate oscillating field but point sources generate spherical waves which are not sinusodial since they are inversely propotional to distance
 
pardesi said:
ues they do generate oscillating field but point sources generate spherical waves which are not sinusodial since they are inversely propotional to distance
The extra spatial dependence is in the E_0(r,t) in the original post.
 
pardesi said:
ues they do generate oscillating field but point sources generate spherical waves which are not sinusodial since they are inversely propotional to distance

Then you need to be more specific and clearer in your question. Recalled that you asked about sources of light, and by "light", we automatically associated EM wave, not static E-field in electrostatics situations.

So you have to figure out exactly what it is here that you want, and ask accordingly.

Zz.
 
sorry i meant solutions of the form [tex]E(x,t)=E_{0}\sin(kx-\omega t)[/tex]
 
We need to work in 3D if we want to talk about real sources.

[tex]E(r,t)=E_{0}\sin(k.r-\omega t)[/tex]

Is an infinite plane wave, no real source can produce such a wave.

It is possible however to express a propagating wave of arbitrary spatial shape as a linear sum of plane wave components, much the same way we can describe a wave with an arbitrary shape in time as a linear sum of discrete sinusoidal frequencies.

Claude.
 
Last edited:

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