Question

In figure two parallel infinitely long current carrying wires are shown. If resultant magnetic field at point $A$ is zero. Then determine current $I$.

• A. 50 A
• B. 15 A
• C. 30 A
• D. 25 A

Answer 1

Answer: (C)

at A B₁ + B₂ = 0
$\frac{{\mu }_0{i}_1}{2\pi r_1}=\frac{{\mu }_{0i_2}}{2\pi r_2}$
$\frac{i_1}{27}=\frac{10}{9}$
$I=30A$