What Is the Electric Field Inside a Solenoid with Time-Varying Current?

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Discussion Overview

The discussion revolves around determining the electric field inside a solenoid when a time-varying current is applied. Participants explore the implications of this scenario on electromagnetic fields, particularly focusing on the relationship between electric and magnetic fields as described by various equations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses confusion regarding the relationship between the electric field and frequency, noting discrepancies between different equations related to time-varying currents.
  • Another participant mentions the quasi-static approximation in the context of time-varying electromagnetic fields, suggesting that the electromagnetic effects propagate at the speed of light.
  • A different participant introduces the concept of intrinsic impedance of free space, stating that if the solenoid is made of a perfect conductor, the ratio of electric to magnetic fields corresponds to this impedance.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the electric field's behavior inside the solenoid with time-varying current. Multiple competing views and interpretations of the equations remain present in the discussion.

Contextual Notes

Participants reference specific equations (e.g., equation (11) and equation (13)) without providing their content, leading to potential gaps in understanding the assumptions or definitions involved. The discussion also lacks clarity on the conditions under which the quasi-static approximation is applicable.

VVS
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Hello,

I am trying to find out the electric field inside a solenoid if a time varying current is passed through.
However I am stuck with these partial differential equations.
View attachment Electric field solenoid.pdf
Somehow I can't solve them and I think something is wrong.
Because according to equation (13) the electric field will vary with frequency sigma/epsilon.
However when looking at equation (11) the electric field must be varying with the frequency of the magnetic field, which is arbitrary.
I am really confused.
Does anybody know the answer?

thanks
VVS
 
Last edited:
Engineering news on Phys.org
Your picture doesn't appear, if you check the picture you uploaded is there than I can be sure to help out
 
SteliosVas said:
Your picture doesn't appear, if you check the picture you uploaded is there than I can be sure to help out

there is no pic ... it's a link to a PDF file to open and it works OK :)


Dave
 
So does nobody have an answer to my question?
 
VVS said:
So does nobody have an answer to my question?



Since you have a time varying current, the electromagnetic field created by the solenoid varies with time. The electromagnetic 'news' travels at the speed of light though. You use the quasi-static approximation
 
If the solenoid is wound with a perfect conductor, and in free space,
then the ratio of the electric field to the magnetic field will be the intrinsic impedance of free space.
Zfs= 4*10-7 * Pi * c = 376.73 ohm
 

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