The magnetic moments associated with two closely wound circular coils A and B of radii $r_{A}$ = 10 cm and $r_{B}$ = 20 cm respectively are equal if: [ $N_{A}I_{A}$ and $N_{B}I_{B}$ are number of turns and current of A and B respectively]
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Question

The magnetic moments associated with two closely wound circular coils A and B of radii $r_{A}$ = 10 cm and $r_{B}$ = 20 cm respectively are equal if: [ $N_{A}I_{A}$ and $N_{B}I_{B}$ are number of turns and current of A and B respectively]

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G1 Physics · Accepted Answer

Magnetic moment M = NIA = NIπr². Equality gives N(A)I(A)(0.10)² = N(B)I(B)(0.20)². Hence N(A)I(A) = 4N(B)I(B).