The magnetic moments associated with two closely wound circular coils A and B of radius rA = 10 cm and rB = 20 cm respectively are equal if: (Where NA, IA and NB, IB are number of turns and current of A and B respectively) (a) 4NA IA = NB IB (b) 2NA IA = NB IB (c) NA = 2NB (d) NA IA = 4NB IB

Answer: (d). m = NIπ r² and rB = 2rA. NA IA π rA² = NB IB π (2rA)² NA IA = 4NB IB, so the answer is (d).

The magnetic moments associated with two closely wound circular coils… | JEE Main 2023 (30 Jan, Shift 1)

Q41JEE Main 2023 · 30 JAN · SHIFT 1Easy

Current Loop as a Magnetic Dipole

The magnetic moments associated with two closely wound circular coils $A$ and $B$ of radius $r_A = 10\text{ cm}$ and $r_B = 20\text{ cm}$ respectively are equal if: (Where $N_A, I_A$ and $N_B, I_B$ are number of turns and current of $A$ and $B$ respectively)

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Answer: (d)

$m = NI\pi r^2$ and $r_B = 2r_A$ .
$N_A I_A \pi r_A^2 = N_B I_B \pi (2r_A)^2$
$N_A I_A = 4N_B I_B$ , so the answer is (d).

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Current Loop as a Magnetic Dipole question from JEE Main 2023 (30 Jan, Shift 1)

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