Induced versus permanent magnetic dipole moments Evaluate the statement: “The induced magnetic dipole moment of a material is independent of its permanent magnetic dipole moment.” Decide whether this statement is true or false in the context of magnetization mechanisms.

Difficulty: Easy

Correct Answer: True

Explanation:


Introduction / Context:
Magnetization arises from two broad mechanisms: (i) field-induced moments (e.g., diamagnetism and the linear part of paramagnetism) and (ii) permanent magnetic dipoles associated with unpaired electron spins and domain structures (paramagnets, ferromagnets). Understanding their independence clarifies magnetic responses across materials.


Given Data / Assumptions:

  • Total magnetic moment is the sum of permanent and induced contributions.
  • Induced moment depends primarily on the applied field and the material’s magnetic polarizability/susceptibility.
  • Permanent moment exists irrespective of the external field (though it can reorient under the field).


Concept / Approach:

The induced magnetic dipole moment is created by the field’s action on electronic orbits/spins and is proportional to the applied field for small fields: m_induced ∝ H (or B). The permanent moment, m_perm, is intrinsic to the material (e.g., unpaired spins, domains). To first order, m_induced is independent of m_perm; the total moment is m_total = m_perm + m_induced. Couplings can exist at large fields or in nonlinear regimes, but the basic statement about independence of the induced component from the inherent permanent moment is correct in standard linear-response theory.


Step-by-Step Solution:

Identify contributions: m_total = m_perm + m_induced.For small fields, m_induced = χ H (linear response).Therefore m_induced is set by χ and H, not by m_perm; hence independence.


Verification / Alternative check:

Materials with zero permanent moments (pure diamagnets) still exhibit induced magnetization; ferromagnets with large permanent moments also show an additional field-induced component (differential susceptibility).


Why Other Options Are Wrong:

Stating “False” assumes dependence; options restricting to special materials or extreme conditions ignore the general linear regime.


Common Pitfalls:

Confusing vector alignment effects of permanent moments with the creation of induced moments; mixing nonlinear saturation behavior with small-signal response.


Final Answer:

True

More Questions from Materials and Components

Discussion & Comments

No comments yet. Be the first to comment!
Join Discussion