Definition check: Magnetization M of a material Consider the statement: “Magnetization of a material is the magnetic dipole moment per unit volume (m^3).” Decide whether this statement is true or false and interpret its engineering relevance for magnetic circuit calculations.

Difficulty: Easy

Correct Answer: True

Explanation:


Introduction / Context:
Magnetization M provides a macroscopic measure of how strongly a material is magnetized under an applied magnetic field. It aggregates microscopic magnetic dipole moments and is central to constitutive relations such as B = μ0 (H + M), widely used in magnetic circuit and device design.


Given Data / Assumptions:

  • M is defined for any magnetizable medium (diamagnetic, paramagnetic, ferromagnetic).
  • Magnetic dipole moment has units of A·m^2.
  • Volume has units of m^3.


Concept / Approach:

By definition, magnetization M equals total magnetic dipole moment per unit volume: M = μ_total / V. In SI units, M has units A/m, consistent with B = μ0 (H + M). This is a general definition and is not restricted to a particular material class or field strength, although the functional dependence M(H) may be linear or nonlinear depending on the material.


Step-by-Step Solution:

Magnetic moment density: M = (magnetic dipole moment) / volume.Units check: (A·m^2) / m^3 = A/m.Conclude the statement is true as a fundamental definition.


Verification / Alternative check:

In linear media, M = χm H, where χm is magnetic susceptibility; substituting into B = μ0 (H + M) recovers B = μ0 (1 + χm) H = μ0 μr H, consistent with standard relations.


Why Other Options Are Wrong:

Limiting the definition to ferromagnets or low fields is unnecessary; the definition is universal even if M(H) behavior varies.


Common Pitfalls:

Confusing M (A/m) with magnetic field strength H (A/m); forgetting that B depends on both H and M.


Final Answer:

True

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