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A planar current loop of N turns, area A, carrying current I, has magnetic moment:
AN I / A
BN I A
CI A / N
DN A / I
Answer & Solution
Correct answer: B. N I A
1. For a single-turn loop the magnetic moment is $m = IA$.
2. With $N$ closely wound turns the moments add: $m = NIA$.
3. Its direction is given by the right-hand thumb rule.
4. The units are A m², consistent with $N I A$.
_Source: NCERT Class 12 Physics Ch 4 "Moving Charges and Magnetism", p.157_
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