Meissner’s Effect

The repulsion of magnetic flux from the interior of a piece of superconducting material as the material undergoes to the transition to the superconducting phase is known as Meissner’s Effect.

Meissner’s Effect

In superconductor

B = 0

µo( H + M ) = 0

M = − H ……………………. (1)

Also, M = χmH ……………. (2)

from (1) & (2)

χmH = − H

χ= − 1 ……………………. (3)

Since, χ= µr − 1 ………… (4)

from (3) & (4)

 µr = 0  (Perfect diamagnetism)

Silsbee Rule

If a superconducting material causes a current such that magnetic field which it produced is equal to the critical field, the superconductivity disappears.

  • The current density at which the superconductivity disappears is known as critical current density.
  • This rule prevents the use of superconductor as coils for the production of the strong magnetic field.
  • The magnetic field requires destroying the superconductivity need not be an external field; it may be internal magnetic field as well.
Meissner’s Effect and Silsbee Rule

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