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{2 I_{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.