Question

Two thin, long, parallel wires, separated by a distance 'd' carry a current of 'i' A in the same direction. They will

• A. Attract each other with a force of $\frac{{\mu }_0{i}^2}{2\pi d^2}$
• B. Repel each other with a force of $\frac{{\mu }_0{i}^2}{2\pi d^2}$
• C. Attract each other with a force of $\frac{{\mu }_0{i}^2}{2\pi d}$
• D. Repel each other with a force of $\frac{{\mu }_0{i}^2}{2\pi d}$

Answer 1

The correct option is C Attract each other with a force of $\frac{{\mu }_0{i}^2}{2\pi d}$

$\left(\frac{F}{l}\right)=\frac{{\mu }_0}{4\pi }.\frac{2i_1{i}_2}{a}\Rightarrow \left(\frac{F}{l}\right)=\frac{{\mu }_0}{4\pi }.\frac{2i^2}{d}=\frac{{\mu }_0{i}^2}{2\pi d}$ (Attractive)