A coil having 100 turns, area of 5 × 10⁻³ m², carrying current of 1 mA is placed in uniform magnetic field of 0.20 T such a way that plane of coil is perpendicular to the magnetic field. The work done in turning the coil through 90° i s _____ μJ.
Physics · Magnetic effect of current · mabnetic moment and torque on current carring loop in magnetic field
JEE Mains 2024 06 Apr Evening Shift

Question

A coil having 100 turns, area of 5 × 10⁻³ m², carrying current of 1 mA is placed in uniform magnetic field of 0.20 T such a way that plane of coil is perpendicular to the magnetic field. The work done in turning the coil through 90° i s _____ μJ.

Physics · Magnetic effect of current · mabnetic moment and torque on current carring loop in magnetic field

JEE Mains 2024 06 Apr Evening Shift

G1 Physics · Accepted Answer

Magnetic dipole moment: M = NIA Potential energy: U = -MB cosθ Initially, the plane of coil is perpendicular to B, so magnetic moment is parallel to B: θᵢ = 0° After rotating by 90°: θf = 90° Work done: W = U(f) - U(i) = 0 - (-MB) = MB Therefore: W = NIAB = 100 × 1 × 10⁻³ × 5 × 10⁻³ × 0.20 = 1 × 10⁻⁴ J = 100 μJ