Question

Two long and parallel straight wires $A$ and $B$ carrying currents of $8.0$ $A$ and $5.0$ $A$ in the same direction are separated by a distance of $4.0$ $cm$. Estimate the force on a $10$ $cm$ section of wire $A$.

Answer 1

Force per unit length $=\frac{F}{l}=\frac{{\mu }_{0}i,i2}{2\pi x}$

$F=\frac{{\mu }_0\times 8\times 5}{2\pi \frac{4}{100}}\times l=\frac{40{\mu }_0}{\frac{8\pi }{100}}\times \frac{10}{100}(l=10cm)$

$F=\frac{40\times 4\pi \times {10}^{-7}\times 10}{8\pi }$

$=2\times {10}^{-5}N$