Question

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

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

Answer 1

The correct option is A $8\times {10}^{-5}N$

Force on $B=B{i}_{B}l$=$\left(\frac{{\mu }_0{i}_A}{2\pi r}\right)i_{B}l$
=$\frac{2\times {10}^{-7}\times 10\times 2\times 2}{10\times {10}^{-2}}$
=$8\times {10}^{-5}N$