Understanding Eddy Currents: Causes, Effects, and Mitigation

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    Currents Eddy currents
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Discussion Overview

The discussion focuses on the concept of eddy currents, exploring their causes, effects, and methods for mitigation. Participants examine the conditions under which eddy currents are induced, the relationship between magnetic fields and conducting materials, and the implications for energy generation.

Discussion Character

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

Main Points Raised

  • One participant suggests that eddy currents are induced when a conducting surface moves through a magnetic field, leading to an opposing magnetic field that slows down the motion.
  • Another participant clarifies that eddy currents are induced only if the magnetic field is changing over time, or if the conductor is moving through a non-uniform magnetic field.
  • A question is raised about the necessity of a non-uniform magnetic field for inducing eddy currents, with an explanation that a uniform field would not create the necessary change.
  • There is a discussion about the concept of magnetic flux and the idea that uniform magnetic fields may not exist outside of specific conditions, such as within solenoids.
  • Participants reference Faraday's Law to explain the basis for eddy currents, emphasizing the importance of changing flux.

Areas of Agreement / Disagreement

Participants generally agree on the conditions required for eddy currents to be induced, but there is some debate regarding the nature of magnetic fields and the implications of uniform versus non-uniform fields. The discussion remains unresolved on the existence of truly uniform magnetic fields.

Contextual Notes

Some assumptions about the nature of magnetic fields and the conditions for inducing eddy currents are not fully explored, and there are unresolved mathematical steps related to the application of Faraday's Law.

DrDanger
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Okay so i just want to make sure i got this right because its a kind of confusing topic for me. So eddy currents are caused because when there is a motion (with a conducting surface) through a magnetic field a current is induced? and because there is a current there is also a magnetic field due to that current which opposes the original magnetic field and causes it to slow down?! Also when people are generating electrical energy by rotating a square/circle loop through a magnetic field do eddy currents slow you down? also I realize by cutting slots and other means you can reduce eddy currents. Thanks for the answers, and i hope my question was clear
 
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You got it pretty much right. But the eddy currents are only induced in a conducting material if the magnetic field is changing with time, or if a conducting material is moving through a magnetic field that is non-uniform (fcn of x, y, z), or rotating in a constant magnetic field.
 
Last edited:
Bob S said:
You got it pretty much right. But the eddy currents are only induced in a conducting material if the magnetic field is changing with time, or if a conducting material is moving through a magnetic field that is non-uniform (fcn of x, y, z), or rotating in a constant magnetic field.
Why does the magnetic field have to be non-uniform?
 
DrDanger said:
Why does the magnetic field have to be non-uniform?

Because something has to change over time; if the conductor moves through a uniform magnetic field, it's functionally static.
 
negitron said:
Because something has to change over time; if the conductor moves through a uniform magnetic field, it's functionally static.
Ahh makes sense now its because there has to be a flux right?, but there is no such thing as a uniform magnetic field right? except inside solenoids, but even then its not exactly uniform right?
 
DrDanger said:
Ahh makes sense now its because there has to be a flux right?, but there is no such thing as a magnetic field right? except inside solenoids, but even then its not exactly uniform right?
The basis for eddy currents is the integral form of Faraday's Law

E dl = -(d/dt) ∫B·dA

where ∫dl is around the perimeter of surface A.

and J = σ E So
" Ahh makes sense now its because there has to be a changing flux right?" Note the d/dt in Faraday's law.
 
Bob S said:
The basis for eddy currents is the integral form of Faraday's Law

E dl = -(d/dt) ∫B·dA

where ∫dl is around the perimeter of surface A.

and J = σ E So
" Ahh makes sense now its because there has to be a changing flux right?" Note the d/dt in Faraday's law.

Thank you for the correction, and yes that is what I mean. Thanks for all the help guys, and the fast responses!
 

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