Question

Two very long, straight, parallel conductors $A$ and $B$ carry current of $5A$ and $10A$ respectively and are at a distance of $10cm$ from each other. The direction of current in two conductors is same. The force acting per unit length between two conductors is: $({\mu }_0=4\pi \times 10^{-7}$ SI unit $)$

• A. $2\times 10^{-4}N{m}^{-1}$ and is attractive
• B. $2\times 10^{-4}N{m}^{-1}$ and is repulsive
• C. $1\times 10^{-4}N{m}^{-1}$ and is attractive
• D. $1\times 10^{-4}N{m}^{-1}$ and is repulsive

Answer 1

Answer: (C)

$\frac{F_M}{\ell }=\frac{{\mu }_0{i}_1{i}_2}{2\pi r}$
$=\frac{4\pi \times 10^{-7}\times 5\times 10}{2\pi \times 0.1}=10^{-4}N/m$