A 2A current carrying straight metal wire of resistance 1 Ω, resistivity 2 × 10⁻⁶ Ωm, area of cross-section 10 mm² and mass 500 g is suspended horizontally in mid air by applying a uniform magnetic field B. The magnitude of B i s ______ × 10⁻¹ T (given, g = 10 m/s²)
Physics · Magnetic effect of current · magnetic force between current carring wire
JEE Mains 2024 05 Apr Morning Shift

Question

A 2A current carrying straight metal wire of resistance 1 Ω, resistivity 2 × 10⁻⁶ Ωm, area of cross-section 10 mm² and mass 500 g is suspended horizontally in mid air by applying a uniform magnetic field B. The magnitude of B i s ______ × 10⁻¹ T (given, g = 10 m/s²)

Physics · Magnetic effect of current · magnetic force between current carring wire

JEE Mains 2024 05 Apr Morning Shift

G1 Physics · Accepted Answer

Resistance relation: R = ρℓ/A Given: R = 1 Ω ρ = 2 × 10⁻⁶ Ωm A = 10 mm² = 10⁻⁵ m² Therefore: 1 = (2 × 10⁻⁶)ℓ/(10⁻⁵) ℓ = 5 m For suspension in equilibrium: mg = BIℓ Therefore: B = mg/(Iℓ) = (0.5 × 10)/(2 × 5) = 0.5 T = 5 × 10⁻¹ T Hence, answer = 5.