Statement check: In ferromagnetic materials (below Curie temperature), neighbouring permanent magnetic dipoles tend to align parallel within a domain. Is this statement correct?
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ATrue
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BFalse
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CTrue only in paramagnetic region
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DTrue only at absolute zero
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EFalse because dipoles are always random
Answer
Correct Answer: True
Explanation
Introduction / Context:Ferromagnetism arises from exchange interactions that energetically favor parallel alignment of neighboring atomic moments. This leads to regions (domains) with spontaneous magnetization even without an external field. Recognizing domain-level alignment clarifies why ferromagnets can be strongly magnetized and exhibit hysteresis.
Given Data / Assumptions:
- Temperature below Curie temperature TC.
- Crystalline ferromagnetic material with domain structure.
- No external field is necessary for spontaneous ordering inside a domain.
Concept / Approach:
Within a magnetic domain, exchange coupling minimizes energy when neighboring spins align parallel, producing a net magnetization. Different domains can orient differently to reduce magnetostatic energy, so a bulk specimen may have near-zero net magnetization until a field reorients domain walls.
Step-by-Step Solution:
Identify temperature regime: below TC → ferromagnetic order possible.Within each domain, spins align parallel due to exchange interactions.Conclude the statement is true for domain interiors.Verification / Alternative check:
Magnetic imaging (e.g., Kerr microscopy) shows domain patterns with uniform magnetization directions separated by domain walls, validating parallel alignment within domains.
Why Other Options Are Wrong:
- False options ignore exchange interaction or conflate with paramagnetism, where alignment is weak and field-induced.
Common Pitfalls:
Confusing domain-level order (parallel inside domains) with macroscopic randomness (different domain orientations) that can yield a small net magnetization without an external field.
Final Answer:
True