Question

Two parallel wires carrying currents $I_1$ and $I_2$ in opposite directions and separated by a distance $d$ experience a

• A. repulsive force ${\mu }_0{I}_1{I}_2/2\pi d$
• B. attractive force ${\mu }_0{I}_1{I}_2/2\pi d$
• C. repulsive force ${\mu }_0{I}_1{I}_2/2\pi d^2$
• D. attractive force ${\mu }_0{I}_1{I}_2/2\pi d^2$

Answer 1

Answer: (A)

The force on straight parallel wires carrying currents $I_1$ and $I_2$ and separated by a distance $d$ is
$F=\frac{{\mu }_0}{4\pi }\frac{2I_1{I}_2}{d}$
$=\frac{{\mu }_0{I}_1{I}_2}{2\pi d}$
Since conductor carries current in opposite direction, so force between them will be repulsive.