Q.

A 2 A current carrying straight metal wire of resistance 1 Ω, resistivity 2×10-6Ωm, 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 is ____ ×10-1T (given, g = 10 m/s²)                           [2024]


Ans.

(5)            R=ρlAl=RAρ=1×10×10-62×10-6=5m

                ilB=mgB=mgil

                B=(0.5)(10)2×5=5×10-1T