The origin of self inductance in a current loop?

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Discussion Overview

The discussion centers around the origin of self-inductance in a current loop, exploring the relationship between electric and magnetic fields. Participants examine theoretical aspects, analogies, and implications of changing magnetic fields in the context of inductance.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Martin questions the origin of induced EMF in a current loop and relates it to the behavior of magnetic fields and electric fields in different reference frames.
  • Some participants assert that the induced EMF arises from the changing magnetic field, as described by Maxwell's equations, particularly when the current decays after the battery is removed.
  • One participant draws an analogy between inductance and mechanical inertia, suggesting that inductors resist changes in current and require a braking force to stop the current flow.
  • Another participant references external sources to discuss the relationship between induction and radiation, indicating a broader context for understanding self-inductance.

Areas of Agreement / Disagreement

Participants express differing views on the origin of self-inductance and the role of changing magnetic fields, with no consensus reached on the explanations provided.

Contextual Notes

Some claims depend on specific interpretations of electromagnetic theory and may require further clarification or assumptions regarding the behavior of fields in various reference frames.

ZeroGravity
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Hi Forum

I am trying to get a better grasp of the relation between electric field and the magnetic field.
The overall question is "What is The origin of selfinductance in a current loop?"
Here are my thourghts:

A battery is connected to a say circular wire with some resistance. The current builds up in the magnetic field and the rest as heat in the wire. The energy U in the magnetic field is U=0.5*L*I^2 L being the selfinductance and I the current. The energy in the magnetic field is "returned" then the battery is removed freom the circuit.

But what is the origin og the Induced EMF(ElectroMotoricForce)?

I know from Feynman's lectures Vol II 13.6. that foro two straight wires the magnetic field from wire one, acts on wire two with a force. But viewed from a refrence frame moving with the electrons, the magnetic field is transformed into an electric field, and the force is now seen as a coulomb force.

Is that the same case for a current loop?

What happens if the reference frame rotates?

Thanks all !
Martin
 
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The induced EMF is due to the changing magnetic field. When the battery is removed from the circuit, the current begins to decay, and so the magnetic field begins to decrease. The changing magnetic field induces an electric field through Maxwells' equation \nabla \times E =- \frac{\partial B}{\partial t}
 
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phyzguy said:
The induced EMF is due to the changing magnetic field. When the battery is removed from the circuit, the current begins to decay, and so the magnetic field begins to decrease. The changing magnetic field induces an electric field through Maxwells' equation \nabla \times E =- \frac{\partial B}{\partial t}
To Zero Gravity: And to take a mechanical analogy, the inductor displays "inertia". It is hard to get the current moving and hard to stop it. The inductor stores energy in its magnetic field and in order to stop the current we need to apply a braking force. This is a reverse voltage, which can be obtained by inserting a high resistance, or opening the switch etc.
 
ZeroGravity said:
I am trying to get a better grasp of the relation between electric field and the magnetic field.
The overall question is "What is The origin of selfinductance in a current loop?"

First take a look at the part titled "Radiation as a Consequence of the Cosmic speed limit" here:
http://physics.weber.edu/schroeder/mrr/MRRtalk.html

And then see the part titled "Compared to the far field" here:
https://en.wikipedia.org/wiki/Near_and_far_field

First link explains origin of radiation, second link explains that induction is related to radiation.
 
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