Question

The force of repulsion between two parallel wires is $f$ when each one of them carries a certain current $I$. If the current in each is doubled, the force between them would be

• A. $\frac{4}{f}$
• B. $4f$
• C. $2f$
• D. $f$

Answer 1

The correct option is B $4f$

Force per unit length between two current carrying conductor is given by ,
$[F=\frac{\left({\mu }_0{I}_1{I}_2\right)}{2\pi d}]$
so, if we doubles the current values the force will become $4$ times.