Question

Two long parallel wires P and Q are both perpendicular to the plane of the paper with distance 5m between them. If P and Q carry current of 2.5A and 5A respectively in the same direction, then the magnetic field at a point halfway between the wires is:

• A. $\frac{\sqrt{3}{\mu }_0}{2\pi }$
• B. $\frac{{\mu }_0}{\pi }$
• C. $\frac{3{\mu }_0}{2\pi }$
• D. $\frac{{\mu }_0}{2\pi }$

Answer 1

The correct option is D $\frac{{\mu }_0}{2\pi }$

At point P
${\overrightarrow{B}}_p=\frac{{\mu }_0\times 2.5}{2\pi \times 2.5}=\frac{{\mu }_0}{2\pi }\otimes$ into the plane
${\overrightarrow{B}}_q=\frac{{\mu }_0\times 5}{2\pi \times 2.5}=\frac{2{\mu }_0}{2\pi }$ out of plane
$B_{net}={\overrightarrow{B}}_q-{\overrightarrow{B}}_p{\overrightarrow{B}}_q>{\overrightarrow{B}}_p=\frac{{\mu }_0}{2\pi }$