Question

Two conductors each of length $12m$ lie parallel to each other in air. The centre to centre distance between the two conductors is $15\times {10}^{-2}m$ and the current in each conductor is $300A$. The force in newton tending to pull the conductors together is:

• A. $14.4N$
• B. $1.44N$
• C. $144N$
• D. $0.144N$

Answer 1

The correct option is B $1.44N$

$F=\frac{{\mu }_0{i}_1{i}_{2}l}{2\pi r}$

$=\frac{2\times {10}^{-7}\times 300\times 300\times 12}{15\times {10}^{-2}}$

$=1\cdot 44N$