Question

Same current ''i'' is flowing in three infinitely long wire along positive x, y and z directions. The magnetic field-at a point (0,0-a) would be

• A. $\frac{{\mu }_{0}i}{2\pi a}(\hat{j}-\hat{i})$
• B. $\frac{{\mu }_{0}i}{2\pi a}(\hat{i}+\hat{j})$
• C. $\frac{{\mu }_{0}i}{2\pi a}(\hat{i}-\hat{j})$
• D. $\frac{{\mu }_{0}i}{2\pi a}(\hat{i}+\hat{j}+\hat{k})$

Answer 1

Answer: (A)

Magnetic field due to current along the z-axis is 0. and due to rest two wires is $\frac{{\mu }_0}{2\pi }\frac{i}{a}$
$B=\frac{{\mu }_{0}i}{2\pi a}j$
$B_y=\frac{{\mu }_{0}i}{2\pi a}(-\hat{i})$
$B_z=0$