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$\quad$$\quad$ B₁ + B₂ = 0
$\frac{\mu_{0}i_{1}}{2\pi r_{1}}=\frac{\mu_{0i_2}}{2\pi r_{2}}$
$\frac{i_{1}}{27}=\frac{10}{9}$
$I=30A$