Twisted Coil in a Magnetic Field

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Discussion Overview

The discussion revolves around the behavior of a twisted coil in a magnetic field, specifically focusing on the induced current and charge accumulation in a circular coil versus a twisted configuration. The scope includes theoretical considerations of electromagnetism and circuit behavior.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes that a homogeneous magnetic field induces a current in a circular coil, leading to a charge Q, and questions how this charge would change when the coil is twisted into an 8-shape with radii a1 and a2.
  • Another participant challenges the notion that charges could accumulate on a conducting coil due to an induced current.
  • A participant reiterates the original question about the charge Q' in the twisted coil, suggesting a relationship based on the areas of the coils involved.
  • One participant clarifies that the total charge circulating due to the induced current is represented by the integral of current over time, indicating that Q is the total charge.
  • Another participant notes that treating the twisted shape as two separate coils complicates the analysis, as the current direction in one half must oppose that in the other half.
  • A participant again mentions the relationship between charge and the capacitor model, asserting that charge conservation must hold true in the system.

Areas of Agreement / Disagreement

Participants express differing views on the accumulation of charge in the twisted coil and the implications of treating the structure as separate coils. There is no consensus on how to approach the problem or the validity of the initial assumptions.

Contextual Notes

Participants have not fully resolved the implications of charge conservation in the context of the twisted coil, and there are unresolved assumptions regarding the treatment of the coil's geometry and current flow.

Leitmotiv
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The idea is as it follows:

We have an homogeneus magnetic field that was increased from 0 to Bf. It induced a certain current (that accumulated to a charge Q) in a circular coil of radius a and resistivity \rho constant. The question is, what would be the charge Q' when the coil is twisted (not strangled), forming an 8 of radii a1 and a2 in terms of Q?

Thanks for your help
 
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I don't see how charges could accumulate on a conducting coil due to an induced current.
 
Leitmotiv said:
The idea is as it follows:

We have an homogeneus magnetic field that was increased from 0 to Bf. It induced a certain current (that accumulated to a charge Q) in a circular coil of radius a and resistivity \rho constant. The question is, what would be the charge Q' when the coil is twisted (not strangled), forming an 8 of radii a1 and a2 in terms of Q?

Thanks for your help
The charge accumulated on a capacitor in series would be Q[a_1^2-a_2^2]/a^2.
 
Nono, I expressed myself terribly. The idea is ALL the charge that circulated due to i is Q, I mean \int i·dt=Q
 
Hmm it seems that in the latter case you can't just treat the 8-shape as two separate coils. For the current to flow in a particular direction in one of the the half-coil, it has to flow in the opposite circular direction. This complicates things somewhat.
 
clem said:
The charge accumulated on a capacitor in series would be Q[a_1^2-a_2^2]/a^2.

The charge is separated by the capacitor.

Charge has to be conserved.
 

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