Question

When two infinitely long parallel wires separated by a distance of $1m$, each carry a current of $3A$, the force in newton/metre length experienced by each will be, (given ${\mu }_0=4\pi \times {10}^{-7}$ S.I. Units).

• A. $2\times {10}^{-7}$
• B. $3\times {10}^{-7}$
• C. $6\times {10}^{-7}$
• D. $18\times {10}^{-7}$

Answer 1

The correct option is D $18\times {10}^{-7}$

$F=ILB$

$B=\frac{{\mu }_o{I}_2}{2\pi d}$

$L=1m$

$I=3A$

$I_2=3A$

$d=1m$

$⟹F=$ $\frac{3\times 1\times 4\pi \times {10}^{-7}\times 3}{2\pi }$ = $18\times {10}^{-7}$ N

Answer. D