Question

Two long straight wires are set parallel to each other. Each carries a current $i$ in the same direction and the separation between them is $2r$. The intensity of the magnetic field midway between them is

• A. ${\mu }_{0}i/r$
• B. $4{\mu }_0^{i/r}$
• C. zero
• D. ${\mu }_0^{i/4r}$

Answer 1

Answer: (C)

$B=\frac{{\mu }_0}{2\pi }\cdot \frac{i}{r}-\frac{{\mu }_0}{2\pi }\cdot \frac{i}{r}=0$