Diamagnetism and permanent dipoles — true or false? “Diamagnetic materials do not possess permanent magnetic dipoles.”
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ATrue
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BFalse
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CTrue only at low temperature
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DFalse; they have aligned permanent moments
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EIndeterminate without hysteresis data
Answer
Correct Answer: True
Explanation
Introduction / Context:Magnetic classifications (dia-, para-, ferro-magnetism) hinge on whether a material has permanent magnetic dipoles and how it responds to an external magnetic field. Diamagnetism is a universal but weak effect present in all materials due to induced currents opposing the applied field.
Given Data / Assumptions:
- Definition: Diamagnetic materials have negative magnetic susceptibility and no intrinsic permanent dipoles.
- Small, linear response in weak fields.
- Room-temperature, zero-bias conditions.
Concept / Approach:In diamagnets, applied fields induce tiny orbital current loops that generate magnetization opposite to the applied field. This induced effect vanishes when the field is removed; there are no permanent unpaired moments as in paramagnets or ferromagnets. Hence the statement is true.
Step-by-Step Solution:Identify property: χ < 0 and no permanent dipoles.Contrast with paramagnetism (unpaired spins → permanent dipoles, χ > 0).Conclude diamagnets lack permanent dipoles → statement true.
Verification / Alternative check:Measured hysteresis for diamagnets shows negligible remanence and coercivity, consistent with absence of permanent dipoles.
Why Other Options Are Wrong:“False” options contradict the definition. Temperature qualifiers or hysteresis prerequisites are unnecessary for this basic classification.
Common Pitfalls:
- Confusing weak ferromagnetism or paramagnetism with diamagnetism.
Final Answer:True