Question

Two wires carry currents of $100A$ and $200A$ respectively and they repel each other with a force of $0.4N/m$. The distance between them will be :

• A. $1m$
• B. $1cm$
• C. $50cm$
• D. $25cm$

Answer 1

The correct option is B $1cm$

Force due to two parallel current carrying conductor is,
$F=\frac{{\mu }_0}{4\pi }\frac{2i_1{i}_2}{r}={10}^{-7}\frac{2\times 100\times 200}{r}$
$\therefore 0.4\times r=4\times {10}^{-3}$
$\therefore r={10}^{-2}m=1cm$