A uniform magnetic field of 2 × 10⁻³ T acts along positive Y-direction. A rectangular loop of sides 20 cm and 10 cm with current of 5 A is Y-Z plane. The current is in anticlockwise sense with reference to negative X axis. Magnitude and direction of the torque is :
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Question

A uniform magnetic field of 2 × 10⁻³ T acts along positive Y-direction. A rectangular loop of sides 20 cm and 10 cm with current of 5 A is Y-Z plane. The current is in anticlockwise sense with reference to negative X axis. Magnitude and direction of the torque is :

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G1 Physics · Accepted Answer

Magnetic moment vector: M⃗ = iA⃗ = 5 × (0.2) × (0.1)(-î) = -0.1î Magnetic field: B⃗ = 2 × 10⁻³ ĵ Torque: τ⃗ = M⃗ × B⃗ = (-0.1î) × (2 × 10⁻³ĵ) = -2 × 10⁻⁴ k̂ N m Therefore, the torque has magnitude 2 × 10⁻⁴ N m and is along negative Z-direction.