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

In summary, the problem is to determine the electric field at the location of a metal ring with radius a in a region with a constant magnetic flux density in the z-direction and a low frequency. Using Faraday's Law, the electric field can be related to the change in magnetic field over time. In cylindrical coordinates, the electric field is directed in the phi direction around the ring. Using the rotation of the electric field and the Maxwell relations, the problem can be solved.
  • #1
beyondlight
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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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  • #2
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.
 

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

What is a metal ring in a magnetic field?

A metal ring in a magnetic field is a small circular piece of metal that is placed within the influence of a magnetic field. The magnetic field exerts a force on the electrons within the metal ring, causing them to move and creating an electric current.

How does a metal ring behave in a magnetic field?

When a metal ring is placed in a magnetic field, the magnetic field exerts a force on the free electrons within the metal. This causes the electrons to move, creating an electric current. The direction of the current depends on the direction of the magnetic field and the orientation of the ring.

What is the purpose of studying a metal ring in a magnetic field?

The study of a metal ring in a magnetic field helps us understand the principles of electromagnetism and how electric currents are affected by magnetic fields. This knowledge is important in many fields, including engineering, physics, and technology.

How is a metal ring in a magnetic field different from a magnet?

A metal ring in a magnetic field is different from a magnet because it is not a permanent magnet. It only exhibits magnetic properties when placed in a magnetic field, whereas a magnet will always have a magnetic field regardless of its surroundings.

Can a metal ring in a magnetic field be used to generate electricity?

Yes, a metal ring in a magnetic field can be used to generate electricity. As the magnetic field exerts a force on the electrons in the metal ring, it creates an electric current. This principle is used in devices such as generators and electric motors.

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