Question

Statement I: The permeability of a ferromagnetic material is independent of the magnetic field.
Statement II: Permeability of a material is a constant quantity.

• A. If both statements are true and statement II is the correct explanation of statement I
• B. If both statements are true but statement II is not the correct explanation of statement I
• C. If statement I is true but statement II is false
• D. If both statements are false

Answer 1

Answer: (D)

The permeability of a ferromagnetic material is not independent of magnetic field, $\vec{B}=\mu_{m} \vec{B}_{0} . \quad B_{0}$ is applied field. The total magnetic field $\vec{B}$ inside a ferromagnet may be $10^{3}$ or $10^{4}$ times the applied field $B_{0} .$ The permeability $\mu_{ m }$ of a ferromagnetic material is not constant, neither the field $\vec{B}$ nor the magnetization $\vec{M} . \vec{M}$ increases linearly with $\vec{B}$ even at small value of $B_{0} .$ From the hysteresis curve, magnetic permeability is greater for lower field.