A straight wire extends from (0, 0, −5m) to (0, 0, +5m) and carries a current of 2A in +z direction. Magnetic field at (3, 4, 0) is
Physics · Magnetic effect of current
JEE Mains NEET

Question

A straight wire extends from (0, 0, −5m) to (0, 0, +5m) and carries a current of 2A in +z direction. Magnetic field at (3, 4, 0) is

G1 Physics · Accepted Answer

For a finite straight wire, B=μ₀I(sinθ₁+sinθ₂)/(4πρ). Here ρ=5 m and θ₁=θ₂=45°, giving magnitude (2√2/5)×10⁻⁷ T. The azimuthal direction at (3,4,0) is proportional to −4î+3ĵ. Hence A.