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Physics · PYQ NEET UG 2017
हिन्दीA \( 250 \)-turn rectangular coil of length \( 2.1\text{ cm} \) and width \( 1.25\text{ cm} \) carries a current of \( 85\text{ }\mu\text{A} \) and subjected to magnetic field of strength \( 0.85\text{ T} \). Work done for rotating the coil by \( 180^\circ \) against the torque is
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Correct answer · Option D
\( 1.15\text{ }\mu\text{J} \)
Explanation
Work done \( W = -MB(\cos 180^\circ - \cos 0^\circ) = 2MB = 2(NIA)B = 2 \times 250 \times 85 \times 10^{-6} \times (2.1 \times 10^{-2} \times 1.25 \times 10^{-2}) \times 0.85 \approx 1.15\text{ }\mu\text{J} \).
