Two long parallel conductors are separated by a distance of $5,\text{cm}$. Each carries a current of $8,\text{A}$ in the same direction. What is the force per unit length on each conductor?

Step-by-step solution

1. Use the formula $f/L=\frac{m{u}_0{I}_1{I}_2}{2pid}$ for force per unit length between parallel currents.
2. Insert ${\mu }_0=4\pi \times 10^{-7},{\text{N/A}}^2$, $I_1=I_2=8,\text{A}$ and $d=0.05,\text{m}$.
3. Compute numerator: ${\mu }_0{I}_1{I}_2=(4\pi \times 10^{-7})\times 64=8.0425\times 10^{-5},\text{N/m}$.
4. Compute denominator: $2\pi d=2\pi \times 0.05=0.314159$.
5. Divide: $8.0425\times 10^{-5},\text{N/m}÷0.314159\approx 2.56\times 10^{-4},\text{N/m}$.
6. State the result as $2.56\times 10^{-4},\text{N/m}$.

Concept tested: force between parallel currents

Published 15 September 2026 · Last updated 16 September 2026 · How this solution was prepared and checked