Magnetic field index of refraction

In summary, a magnetic field does not refract when it enters into a different medium with a different permeability.
  • #1
mcjosep
35
0
Does a magnetic field refract when it enters into a different medium?
 
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  • #2
Yes. In going from air into a medium with permeability u at an angle, H-parallel is continuous at the boundary, and the normal component of B=uH is continuous at the boundary, so the B lines appear to "refract" as they enter the medium with permeability u. So u is the equivalent of the index of refraction in dielectrics.



Bob S
 
  • #3
More precisely, u is the equivalent of epsilon and determines the refraction in magnetostatic situations. The refractive index determines the refraction of electromagnetic waves i.e. of both their electric and magnetic field components.
 
  • #4
Hm, the magnetic field changes direction, but it doesn't refract (in the strict sense of the word), as refraction is a wave phenomenon. Giving a easier example: when Earth orbits around the Sun, it constantly changes direction, but it's not refracting. Of course, when a magnetic field is part of a electromagnetic wave, then both the wave and the magnetic field change direction (except in normal incidence, of course), but we can only say the wave has refracted. The maximum we can say about the magnetic field is that it has changed direction.

@DrDu: well, not quite.
You can say the whole wave refracts, but its constituent electric and magnetic fields don't refract, since the aren't waves. And u isn't the "refraction index" for the magnetostatic case, for the same reasons.
 
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  • #5
The question is really a bit too open, I think. "When it enters" sounds like some energy flow (i.e. wave) is involved / implied.

In any case, if not referring to a wave, why should a magnetic 'field line' not have its direction modified across a boundary? If current flow and Electric fields change, what's so unimaginable?
 
  • #6
My earlier post referred to static magnetic field B lines crossing a magnetic boundary from one permeability to another, where my statement that the direction of the "field lines appear to "refract" " is nearly equivalent to a "Snell's Law" sin i/sin r = μ. Because this is a magnetostatic case, there is no wavelength or wave velocity involved. Because μ is usually >>1 in most magnetic materials, the magnetic field lines inside the permeable material are usually nearly perpendicular to the boundary.

Bob S
 
  • #7
Bob : I am very interested in your modified "Snell's Law" sin i/sin r = μ. How is this derived/proved ?

Alan P
 
  • #8
The 'refraction' could be Tan r/Tan i = 1/μ. See webmit.edu/6.013_book/www/chapter9/9.6.html

Alan Payne
 

What is the magnetic field index of refraction?

The magnetic field index of refraction is a measure of how much a magnetic field affects the velocity of light passing through a material. It is denoted by the symbol μ and is related to the magnetic permeability of the material.

How is the magnetic field index of refraction different from the ordinary index of refraction?

The ordinary index of refraction, denoted by the symbol n, measures how much a material slows down the speed of light. It is affected by the material's electrical properties, while the magnetic field index of refraction takes into account the material's magnetic properties.

What factors can affect the magnetic field index of refraction?

The magnetic field index of refraction is affected by the material's magnetic permeability, which can vary depending on factors such as temperature, pressure, and the strength of the applied magnetic field. Other factors, such as the material's structure and composition, can also play a role.

How is the magnetic field index of refraction measured?

The magnetic field index of refraction is typically measured using a device called a Faraday rotation spectrometer. This instrument measures the rotation of polarized light passing through a material under the influence of a magnetic field, allowing for the calculation of the magnetic field index of refraction.

What are some real-world applications of the magnetic field index of refraction?

The magnetic field index of refraction has important applications in fields such as optics, telecommunications, and materials science. It is used to study the magnetic properties of materials, to design high-performance optical devices, and to optimize the efficiency of magnetic storage and communication systems.

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