Magnetic Permeability: Temperature Effects

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Discussion Overview

The discussion revolves around the effects of temperature on magnetic permeability, particularly in the context of superconductivity and the Meissner effect. Participants explore theoretical implications and potential applications related to magnetic fields and electricity generation.

Discussion Character

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

Main Points Raised

  • One participant questions whether the magnetic permeability of a metal remains constant regardless of temperature, including at superconducting temperatures.
  • Another participant discusses the Meissner effect, noting that while it allows a magnet to float, the large reluctance may limit this effect unless the relative permeability is artificially reduced.
  • There is a suggestion that the Meissner effect involves current loops that create opposing magnetic fields in a semiconductor, although the understanding of this mechanism is limited among participants.
  • Participants ponder the possibility of using the reaction field from the Meissner effect to generate electricity, questioning the advantages and the source of original energy for such a process.
  • One participant speculates that the opposing field in the semiconductor may equal the external flux but is not strong enough to be detected by a coil, suggesting that while there may be a magnetic field strength (H), the magnetic flux density (B) could be zero.

Areas of Agreement / Disagreement

Participants express uncertainty and differing views on the nature of magnetic permeability at varying temperatures and the mechanisms behind the Meissner effect. The discussion remains unresolved with multiple competing ideas presented.

Contextual Notes

Participants acknowledge gaps in their understanding of the Meissner effect and its implications for electricity generation, indicating a need for further exploration of the underlying physics.

Narayanan KR
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TL;DR
Is the superconductor in meissner effect able to completely repel external magnetic fields because it provides large magnetic reluctance(small permeability) thereby forcing the external flux to chose alternate paths of low reluctance as shown in case 1 electrical equivalent or is it because an equal and opposite field gets produced by current loops inside the superconductor(T<Tc) as shown by case 2 circuit
If it is case 2 then can this reaction field be harnessed by a coil for electricity ?
meissner1.jpg

One more thing i forgot to add, is magnetic permeability of a metal constant irrespective of its temperature including superconducting temperature ?
 
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The Meissner effect can make the magnet float, but the large reluctance seems unable to do this.

In addition, under the same size ratio, the maximum reluctance will be limited by the permeability of free space, unless we artificially reduce the relative permeability to less than 1.
 
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alan123hk said:
The Meissner effect can make the magnet float, but the large reluctance seems unable to do this.

In addition, under the same size ratio, the maximum reluctance will be limited by the permeability of free space, unless we artificially reduce the relative permeability to less than 1.
so the meissner effect is due to current loops followed by opposing magnetic fields created in the semiconductor ?
 
Narayanan KR said:
so the meissner effect is due to current loops followed by opposing magnetic fields created in the semiconductor ?
It seems that the situation is not far from what you said.

Narayanan KR said:
Can the coil use this reaction field to generate electricity?

In fact, I don't know much about how the Meissner effect works.
But if you want to use it to generate electricity, what do you think of its advantages and where the original energy comes from ?
 
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alan123hk said:
It seems that the situation is not far from what you said.
In fact, I don't know much about how the Meissner effect works.
But if you want to use it to generate electricity, what do you think of its advantages and where the original energy comes from ?
i guess the opposing field in the semiconductor is equal to external flux but never large enough to allow itself to be detected by a coil, it may have H but B=0
 

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