Question

Currents of 10 A and 2 A are passed through two parallel wires A and B respectively in opposite directions. If the wire A is infinitely long and length of the wire B is 2 m, the force acting on the conductor B which is situated at 10 cm distance from A will be

• A. $5 \times 10^{-5}N$
• B. $4 \pi \times 10^{-7}N$
• C. $8 \times 10^{-5}N$
• D. $8\pi \times 10^{-7}N$

Answer 1

The Correct Option is C

Force on a conductor of length l, carrying current $I_2$ and placed at a distance r parallel to another infinitely long conductor carrying current $I_1 \, is $ $\hspace5mm F=\frac {\mu _0}{4 \pi }. \frac {2I_1I_2}{r}l$ Here $\hspace5mm I_1=10 \, A, I_2=2 \, A,l=2 \, m, $ $\hspace5mm r=10cm=0.1m$ $\therefore \hspace5mm F=10^{-7}\times \frac {2 \times 10 \times 2 \times 2}{0.1} $ $\hspace5mm =8 \times 10^{-5}N $