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Physics · PYQ NEET UG 2021
हिन्दीA uniform conducting wire of length \( 12a \) and resistance \( R \) is wound up as a current carrying coil in the shape of, (i) an equilateral triangle of side \( a \). (ii) a square of side \( a \). The magnetic dipole moments of the coil in each case respectively are:
Correct answer · Option 4
\( \sqrt{3} Ia^2 \) and \( 3Ia^2 \)
Explanation
For equilateral triangle, turns \( N_1 = \frac{12a}{3a} = 4 \), area \( A_1 = \frac{\sqrt{3}}{4}a^2 \), \( M_1 = N_1 I A_1 = 4I(\frac{\sqrt{3}}{4}a^2) = \sqrt{3}Ia^2 \). For square, turns \( N_2 = \frac{12a}{4a} = 3 \), area \( A_2 = a^2 \), \( M_2 = N_2 I A_2 = 3Ia^2 \).
