Magnetic materials: choose the incorrect statement about magnetic behavior and material selection for permanent magnets versus electromagnets.

Introduction:
Different applications demand different magnetic properties. Electromagnets used for transformers and motors prioritize low losses and high permeability, while permanent magnets require high coercivity and remanence to retain magnetization without an external field. Understanding which statements align with these principles helps in material selection and design.

Given Data / Assumptions:

• Terminology: 'soft' versus 'hard' magnetic refers to coercivity and hysteresis behavior, not mechanical hardness.
• Curie temperature marks the transition from ferromagnetic to paramagnetic behavior.
• Examples: pure iron (soft), tungsten steel and alnico (hard).

Concept / Approach:
Soft magnetic materials exhibit high initial permeability, low coercive force, and low hysteresis loss—ideal for alternating fields. Hard magnetic materials have high coercivity and retain magnetization, suitable for permanent magnets. Above the Curie point, even ferromagnets lose ordered domains and behave paramagnetically, confirming option (a). Alnico and tungsten steel are classic hard magnet materials, contradicting any statement that claims they are not hard magnetic.

Step-by-Step Solution:
Evaluate each statement against standard definitions and examples.Identify the outlier: the claim that tungsten steel and alnico are not hard magnetic is false.Mark this as the incorrect ('wrong') statement.

Verification / Alternative check:
Magnetics references classify tungsten steel and alnico as traditional permanent-magnet materials with substantial coercive force and remanence.

Why Other Options Are Wrong:

• (a): Correct: Curie transition removes ferromagnetism.
• (b): Correct distinction between permanent magnets and electromagnet cores.
• (c): Correct properties of soft magnets such as low loss and high permeability.
• (e): Correct by definition for hard magnets.

Common Pitfalls:
Confusing mechanical 'hardness' with magnetic 'hardness'; they are different properties influenced by microstructure and composition.

Final Answer:
Tungsten steel and alnico are not hard magnetic materials.