Maxwell's Equations: Draw State of Polarization & Find B(x,t)

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Homework Help Overview

The discussion revolves around the state of polarization of an electromagnetic wave and the application of Faraday's law to find the magnetic field B(x,t) associated with it. The original poster describes the wave as circularly polarized and seeks guidance on using Faraday's law for their calculations.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to describe the polarization state and expresses uncertainty about applying Faraday's law. They mention breaking down the law into its vector form but are unsure of their approach. Other participants provide clarifications on the electric field representation and suggest ways to compute the magnetic field using the law.

Discussion Status

Participants are actively engaging with the problem, with some providing insights into the relationship between the electric and magnetic fields. There is no explicit consensus yet, but helpful guidance has been offered regarding the application of Faraday's law and the representation of the electric field.

Contextual Notes

There are indications of missing information, particularly regarding the correct form of the equations being discussed. The original poster also notes constraints related to formatting issues in their posts.

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Homework Statement



Draw the state of polarization of the electromagnetic (EM) wave defined by

*****PLEASE NOTE EQUATION SHOWN IN NEXT POST****** (For some reason can't change it in this post...

with Eo real. Use a sentence to describe in words the state of polarization of this EM wave.

Use the differential form of Faraday's law to obtain B(x,t) for the same EM wave


Homework Equations



*****PLEASE NOTE EQUATION SHOWN IN NEXT POST****** (For some reason can't change it in this post...

The Attempt at a Solution



I have done the first part and found the EM wave to be circularly polarized (anticlockwise) with an amplitude of E0

i am unsure how to use faradays law. I tried breaking the LHS of faraday into its respective partial differential vector form, which i am currently working my way through but i am fairly sure it is wrong!

Any ideas on how to apply to get the magnetic field from the electric using faraday-maxwell's law would be greatly appreciated!

Many Thanks
 
Last edited:
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Sorry i copied and pasted the equation and it has come out wrong...

It should read

E(x,t) = Eo( y + e^(i3[tex]\Pi[/tex]/2) z )e^(i(kx-[tex]\omega[/tex]t)) ,


Bold Letters denote unit vectors

Relevant Equations;

[tex]\nabla[/tex] x E = - [tex]\partial[/tex]B / [tex]\partial[/tex] t (Faraday-Maxwell Equation)

Excuse my mistake!
 
Last edited:
Your electric field is given by

[tex] \mathbf{E}=E(x,y,z,t)=E_0\exp[i(kx-\omega t)]\hat{\mathbf{y}}+E_0\exp[i(kx-\omega t)]\exp\left[i\frac{3\pi}{2}\right]\hat{\mathbf{z}}[/tex]

correct? But we also know [itex]\mathbf{E}=Re(\mathbf{E}'\exp[i\omega t])[/itex] where [itex]\mathbf{E}'[/itex] is the spatial component of the electric field. Then through Faraday's law,

[tex] \mathbf{B}'=-\frac{1}{i\omega}\nabla\times\mathbf{E}'[/tex]

You can then solve [itex]\mathbf{B}=Re(\mathbf{B}'\exp[i\omega t])[/itex].
 
Now that I've had a good night's rest, you can actually ignore the fact that I said the real components of the spatial electric and magnetic components. This would only be true if your original electric field were given by cosine.
 
Thank you, that really helps! I appreciate it!
 

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