BITSAT2015PhysicsMagnetic Effects of CurrentActual
A long straight wire along the Z -axis carries a current I in the negative Z -direction. The magnetic vector field B at a point having coordinates (x, y) in the Z=0 plane is
Options
- A₀ I(y i -x j ) 2 (x²+y² )
- B₀ I(x i +y j ) 2 (x²+y² )
- C₀ I(x j -y i ) 2 (x²+y² )
- D₀ I(x i -y j ) 2 (x²+y² )
Correct answer
A. ₀ I(y i -x j ) 2 (x²+y² )
Step-by-step solution
The wire carries a current I in the negative z -direction. We have to consider the magnetic vector field B at (x, y) in the z=0 plane. Magnetic field B is perpendicular to O P B =B i -B j array l = y r , = x r B= ₀ I 2 r B = ₀ I 2 r² (y i -x j ) array or B = ₀ I(y i -x j ) 2 (x²+y² )