Finding the Electric Field for a Metal Ring in a Magnetic Field

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SUMMARY

The discussion focuses on calculating the electric field generated in a metal ring of radius 'a' placed in a homogeneous magnetic field described by the equation \(\hat{B} = \hat{z}B_0 \cos(\omega t)\). Utilizing Faraday's Law, which states \(\nabla \times E = -\frac{dB}{dt}\), the electric field is determined to be directed in the \(\varphi\) direction around the ring. The initial attempt at the solution involves cylindrical coordinates and leads to the equation \(-\frac{dE_{\varphi}}{dz}\hat{r} + \frac{1}{r} \frac{d(rE_{\varphi})}{dr}\hat{z} = \hat{z}B_0 \omega \sin(\omega t)\). The discussion emphasizes the importance of starting from Maxwell's relations for a correct approach.

PREREQUISITES
  • Understanding of Faraday's Law of Electromagnetic Induction
  • Familiarity with cylindrical coordinate systems
  • Knowledge of Maxwell's equations
  • Basic concepts of electromotive force (emf) and electric fields
NEXT STEPS
  • Study the derivation of Faraday's Law in detail
  • Explore the relationship between electric field and electromotive force (emf)
  • Investigate the application of Maxwell's equations in electromagnetic theory
  • Learn about the behavior of electric fields in varying magnetic fields
USEFUL FOR

Students of electromagnetism, physics enthusiasts, and anyone studying the principles of electric fields in magnetic environments will benefit from this discussion.

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Homework Statement



A metal ring of radius a is located in a region with the homogenous magnetic flux density:

[itex]\hat{B} =\hat{z}B_0 cos(\omega t)[/itex]

The metal ring coincides with the plane z=0. The frequency w is very low.

Use Faraday´s Law to determine the electric field where the metal ring is located

Homework Equations



Faraday´s Law

[itex]\nabla \times E= -\frac{dB}{dt}[/itex]

The Attempt at a Solution

Cylindrical coordinates.

The Electric field is directed in the [itex]\varphi[/itex] direction around the ring.Rotation of E then becomes:

[itex]-\frac{dE_{\varphi}}{dz}\hat{r} + \frac{1}{r} \frac{d(rE_{\varphi})}{dr}\hat{z}[/itex] = [itex]\hat{z}B_0 \omega sin(\omega t)[/itex]Is this a correct beginning, and how do i proceed from this point?
 
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It's admirable to start from the Maxwell relations explicitly. Most people probably would not.

hint: what is Faraday's law?
hint: what relates emf and electric field?

I'm actually looking at your approach, it should of course yield the same result, will be either fun or frustration for me.
 

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