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

I₁ = 8.0 A
I₂ = 5.0 A
r = 4.0 cm = 4.0 x 10^-2 m
l = 10 cm = 0.1 m
F = $\frac{2\times {10}^{-7}{\mathrm{I}}_1{\mathrm{I}}_{2}l}{\mathrm{r}}$
= $\frac{2\times {10}^{-7}\times 8\times 5\times 0.1}{4\times {10}^{-2}}$
= 2 x 10^-5 N (towards B)