Question

Two thin long parallel wires separated by a distance $d$ carry a current of $I$ ampere in same direction. They will

• A. attract each other with a force of $\frac{{\mu }_0{I}^2}{2\pi d}$
• B. repel each other with a force of $\frac{{\mu }_0{I}^2}{2\pi d}$
• C. attract each other with a force of $\frac{{\mu }_0{I}^2}{2\pi d^2}$
• D. repel each other with a force of $\frac{{\mu }_0{I}^2}{2\pi d^2}$

Answer 1

Answer: (A)

Current flows in same direction.
$\therefore$ Wires attract each other and $\frac{F}{l}=\frac{{\mu }_0{I}^2}{2\pi d}$